diff --git a/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java b/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java
index 32bfd5d28..5008809f7 100644
--- a/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java
+++ b/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 
 import javax.persistence.criteria.CriteriaBuilder;
@@ -35,8 +36,10 @@ import javax.persistence.metamodel.SingularAttribute;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.domain.Example;
 import org.springframework.data.domain.ExampleMatcher;
+import org.springframework.data.domain.ExampleMatcher.PropertyValueTransformer;
 import org.springframework.data.repository.core.support.ExampleMatcherAccessor;
 import org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper;
+import org.springframework.lang.Nullable;
 import org.springframework.orm.jpa.JpaSystemException;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -60,7 +63,7 @@ public class QueryByExamplePredicateBuilder {
 	private static final Set<PersistentAttributeType> ASSOCIATION_TYPES;
 
 	static {
-		ASSOCIATION_TYPES = new HashSet<PersistentAttributeType>(Arrays.asList(PersistentAttributeType.MANY_TO_MANY,
+		ASSOCIATION_TYPES = new HashSet<>(Arrays.asList(PersistentAttributeType.MANY_TO_MANY,
 				PersistentAttributeType.MANY_TO_ONE, PersistentAttributeType.ONE_TO_MANY, PersistentAttributeType.ONE_TO_ONE));
 	}
 
@@ -100,7 +103,7 @@ public class QueryByExamplePredicateBuilder {
 	static List<Predicate> getPredicates(String path, CriteriaBuilder cb, Path<?> from, ManagedType<?> type, Object value,
 			Class<?> probeType, ExampleMatcherAccessor exampleAccessor, PathNode currentNode) {
 
-		List<Predicate> predicates = new ArrayList<Predicate>();
+		List<Predicate> predicates = new ArrayList<>();
 		DirectFieldAccessFallbackBeanWrapper beanWrapper = new DirectFieldAccessFallbackBeanWrapper(value);
 
 		for (SingularAttribute attribute : type.getSingularAttributes()) {
@@ -111,10 +114,11 @@ public class QueryByExamplePredicateBuilder {
 				continue;
 			}
 
-			Object attributeValue = exampleAccessor.getValueTransformerForPath(currentPath)
-					.convert(beanWrapper.getPropertyValue(attribute.getName()));
+			PropertyValueTransformer transformer = exampleAccessor.getValueTransformerForPath(currentPath);
+			Optional<Object> optionalValue = transformer
+					.apply(Optional.ofNullable(beanWrapper.getPropertyValue(attribute.getName())));
 
-			if (attributeValue == null) {
+			if (!optionalValue.isPresent()) {
 
 				if (exampleAccessor.getNullHandler().equals(ExampleMatcher.NullHandler.INCLUDE)) {
 					predicates.add(cb.isNull(from.get(attribute)));
@@ -122,6 +126,8 @@ public class QueryByExamplePredicateBuilder {
 				continue;
 			}
 
+			Object attributeValue = optionalValue.get();
+
 			if (attribute.getPersistentAttributeType().equals(PersistentAttributeType.EMBEDDED)) {
 
 				predicates.addAll(getPredicates(currentPath, cb, from.get(attribute.getName()),
@@ -132,8 +138,8 @@ public class QueryByExamplePredicateBuilder {
 			if (isAssociation(attribute)) {
 
 				if (!(from instanceof From)) {
-					throw new JpaSystemException(new IllegalArgumentException(
-							String.format("Unexpected path type for %s. Found %s where From.class was expected.", currentPath, from)));
+					throw new JpaSystemException(new IllegalArgumentException(String
+							.format("Unexpected path type for %s. Found %s where From.class was expected.", currentPath, from)));
 				}
 
 				PathNode node = currentNode.add(attribute.getName(), attributeValue);
@@ -197,11 +203,11 @@ public class QueryByExamplePredicateBuilder {
 	private static class PathNode {
 
 		String name;
-		PathNode parent;
-		List<PathNode> siblings = new ArrayList<PathNode>();;
-		Object value;
+		@Nullable PathNode parent;
+		List<PathNode> siblings = new ArrayList<>();
+		@Nullable Object value;
 
-		public PathNode(String edge, PathNode parent, Object value) {
+		PathNode(String edge, @Nullable PathNode parent, @Nullable Object value) {
 
 			this.name = edge;
 			this.parent = parent;
@@ -222,14 +228,14 @@ public class QueryByExamplePredicateBuilder {
 			}
 
 			String identityHex = ObjectUtils.getIdentityHexString(value);
-			PathNode tmp = parent;
+			PathNode current = parent;
 
-			while (tmp != null) {
+			while (current != null) {
 
-				if (ObjectUtils.getIdentityHexString(tmp.value).equals(identityHex)) {
+				if (ObjectUtils.getIdentityHexString(current.value).equals(identityHex)) {
 					return true;
 				}
-				tmp = tmp.parent;
+				current = current.parent;
 			}
 
 			return false;
diff --git a/src/main/java/org/springframework/data/jpa/convert/package-info.java b/src/main/java/org/springframework/data/jpa/convert/package-info.java
new file mode 100644
index 000000000..a19e27cbb
--- /dev/null
+++ b/src/main/java/org/springframework/data/jpa/convert/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Spring Data JPA specific converter infrastructure.
+ */
+@NonNullApi
+package org.springframework.data.jpa.convert;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/convert/threeten/package-info.java b/src/main/java/org/springframework/data/jpa/convert/threeten/package-info.java
new file mode 100644
index 000000000..4c7354fa5
--- /dev/null
+++ b/src/main/java/org/springframework/data/jpa/convert/threeten/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Spring Data JPA specific JSR-310 converters.
+ */
+@NonNullApi
+package org.springframework.data.jpa.convert.threeten;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/convert/threetenbp/package-info.java b/src/main/java/org/springframework/data/jpa/convert/threetenbp/package-info.java
new file mode 100644
index 000000000..94a0241e5
--- /dev/null
+++ b/src/main/java/org/springframework/data/jpa/convert/threetenbp/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Spring Data JPA specific ThreeTenBp converters.
+ */
+@NonNullApi
+package org.springframework.data.jpa.convert.threetenbp;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/domain/AbstractAuditable.java b/src/main/java/org/springframework/data/jpa/domain/AbstractAuditable.java
index 328982f2d..259e6b700 100644
--- a/src/main/java/org/springframework/data/jpa/domain/AbstractAuditable.java
+++ b/src/main/java/org/springframework/data/jpa/domain/AbstractAuditable.java
@@ -27,12 +27,14 @@ import javax.persistence.Temporal;
 import javax.persistence.TemporalType;
 
 import org.springframework.data.domain.Auditable;
+import org.springframework.lang.Nullable;
 
 /**
  * Abstract base class for auditable entities. Stores the audition values in persistent fields.
  * 
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @param <U> the auditing type. Typically some kind of user.
  * @param <PK> the type of the auditing type's idenifier
  */
@@ -43,16 +45,16 @@ public abstract class AbstractAuditable<U, PK extends Serializable> extends Abst
 	private static final long serialVersionUID = 141481953116476081L;
 
 	@ManyToOne //
-	private U createdBy;
+	private @Nullable U createdBy;
 
 	@Temporal(TemporalType.TIMESTAMP) //
-	private Date createdDate;
+	private @Nullable Date createdDate;
 
 	@ManyToOne //
-	private U lastModifiedBy;
+	private @Nullable U lastModifiedBy;
 
 	@Temporal(TemporalType.TIMESTAMP) //
-	private Date lastModifiedDate;
+	private @Nullable Date lastModifiedDate;
 
 	/*
 	 * (non-Javadoc)
diff --git a/src/main/java/org/springframework/data/jpa/domain/AbstractPersistable.java b/src/main/java/org/springframework/data/jpa/domain/AbstractPersistable.java
index 706570c7e..87de1a9db 100644
--- a/src/main/java/org/springframework/data/jpa/domain/AbstractPersistable.java
+++ b/src/main/java/org/springframework/data/jpa/domain/AbstractPersistable.java
@@ -23,6 +23,7 @@ import javax.persistence.MappedSuperclass;
 import javax.persistence.Transient;
 
 import org.springframework.data.domain.Persistable;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -31,6 +32,7 @@ import org.springframework.util.ClassUtils;
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  * @param <PK> the type of the identifier.
  */
 @MappedSuperclass
@@ -38,13 +40,13 @@ public abstract class AbstractPersistable<PK extends Serializable> implements Pe
 
 	private static final long serialVersionUID = -5554308939380869754L;
 
-	@Id @GeneratedValue private PK id;
+	@Id @GeneratedValue private @Nullable PK id;
 
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.domain.Persistable#getId()
 	 */
-	public PK getId() {
+	public @Nullable PK getId() {
 		return id;
 	}
 
@@ -53,7 +55,7 @@ public abstract class AbstractPersistable<PK extends Serializable> implements Pe
 	 * 
 	 * @param id the id to set
 	 */
-	protected void setId(final PK id) {
+	protected void setId(@Nullable PK id) {
 		this.id = id;
 	}
 
diff --git a/src/main/java/org/springframework/data/jpa/domain/JpaSort.java b/src/main/java/org/springframework/data/jpa/domain/JpaSort.java
index 7d2045777..ef784725f 100644
--- a/src/main/java/org/springframework/data/jpa/domain/JpaSort.java
+++ b/src/main/java/org/springframework/data/jpa/domain/JpaSort.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import javax.persistence.metamodel.Attribute;
 import javax.persistence.metamodel.PluralAttribute;
 
 import org.springframework.data.domain.Sort;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -81,7 +82,7 @@ public class JpaSort extends Sort {
 	}
 
 	@SuppressWarnings("deprecation")
-	private JpaSort(List<Order> orders, Direction direction, List<Path<?, ?>> paths) {
+	private JpaSort(List<Order> orders, @Nullable Direction direction, List<Path<?, ?>> paths) {
 		super(combine(orders, direction, paths));
 	}
 
@@ -97,7 +98,7 @@ public class JpaSort extends Sort {
 	 * @param attributes must not be {@literal null}.
 	 * @return
 	 */
-	public JpaSort and(Direction direction, Attribute<?, ?>... attributes) {
+	public JpaSort and(@Nullable Direction direction, Attribute<?, ?>... attributes) {
 
 		Assert.notNull(attributes, "Attributes must not be null!");
 
@@ -111,7 +112,7 @@ public class JpaSort extends Sort {
 	 * @param paths must not be {@literal null}.
 	 * @return
 	 */
-	public JpaSort and(Direction direction, Path<?, ?>... paths) {
+	public JpaSort and(@Nullable Direction direction, Path<?, ?>... paths) {
 
 		Assert.notNull(paths, "Paths must not be null!");
 
@@ -131,7 +132,7 @@ public class JpaSort extends Sort {
 	 * @param properties must not be {@literal null} or empty.
 	 * @return
 	 */
-	public JpaSort andUnsafe(Direction direction, String... properties) {
+	public JpaSort andUnsafe(@Nullable Direction direction, String... properties) {
 
 		Assert.notEmpty(properties, "Properties must not be null!");
 
@@ -168,7 +169,7 @@ public class JpaSort extends Sort {
 		return paths;
 	}
 
-	private static List<Order> combine(List<Order> orders, Direction direction, List<Path<?, ?>> paths) {
+	private static List<Order> combine(List<Order> orders, @Nullable Direction direction, List<Path<?, ?>> paths) {
 
 		List<Order> result = new ArrayList<Sort.Order>(orders);
 
@@ -331,7 +332,7 @@ public class JpaSort extends Sort {
 		 * @param direction can be {@literal null}, will default to {@link Sort#DEFAULT_DIRECTION}.
 		 * @param property must not be {@literal null}.
 		 */
-		private JpaOrder(Direction direction, String property) {
+		private JpaOrder(@Nullable Direction direction, String property) {
 			this(direction, property, NullHandling.NATIVE);
 		}
 
@@ -343,11 +344,11 @@ public class JpaSort extends Sort {
 		 * @param property must not be {@literal null}.
 		 * @param nullHandlingHint can be {@literal null}, will default to {@link NullHandling#NATIVE}.
 		 */
-		private JpaOrder(Direction direction, String property, NullHandling nullHandlingHint) {
+		private JpaOrder(@Nullable Direction direction, String property, NullHandling nullHandlingHint) {
 			this(direction, property, nullHandlingHint, false, true);
 		}
 
-		private JpaOrder(Direction direction, String property, NullHandling nullHandling, boolean ignoreCase,
+		private JpaOrder(@Nullable Direction direction, String property, NullHandling nullHandling, boolean ignoreCase,
 				boolean unsafe) {
 
 			super(direction, property, nullHandling);
diff --git a/src/main/java/org/springframework/data/jpa/domain/Specification.java b/src/main/java/org/springframework/data/jpa/domain/Specification.java
index d30728fc7..696f791c7 100644
--- a/src/main/java/org/springframework/data/jpa/domain/Specification.java
+++ b/src/main/java/org/springframework/data/jpa/domain/Specification.java
@@ -24,6 +24,8 @@ import javax.persistence.criteria.CriteriaQuery;
 import javax.persistence.criteria.Predicate;
 import javax.persistence.criteria.Root;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Specification in the sense of Domain Driven Design.
  * 
@@ -31,6 +33,7 @@ import javax.persistence.criteria.Root;
  * @author Thomas Darimont
  * @author Krzysztof Rzymkowski
  * @author Sebastian Staudt
+ * @author Mark Paluch
  */
 @SuppressWarnings("deprecation")
 public interface Specification<T> extends Serializable {
@@ -91,5 +94,6 @@ public interface Specification<T> extends Serializable {
 	 * @param query
 	 * @return a {@link Predicate}, may be {@literal null}.
 	 */
+	@Nullable
 	Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb);
 }
diff --git a/src/main/java/org/springframework/data/jpa/domain/Specifications.java b/src/main/java/org/springframework/data/jpa/domain/Specifications.java
index 20dd8b21c..affd73589 100644
--- a/src/main/java/org/springframework/data/jpa/domain/Specifications.java
+++ b/src/main/java/org/springframework/data/jpa/domain/Specifications.java
@@ -24,12 +24,16 @@ import javax.persistence.criteria.CriteriaQuery;
 import javax.persistence.criteria.Predicate;
 import javax.persistence.criteria.Root;
 
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
 /**
  * Helper class to easily combine {@link Specification} instances.
  *
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Sebastian Staudt
+ * @author Mark Paluch
  * @deprecated since 2.0, use factory methods on {@link Specification} instead.
  */
 @Deprecated
@@ -37,14 +41,14 @@ public class Specifications<T> implements Specification<T>, Serializable {
 
 	private static final long serialVersionUID = 1L;
 
-	private final Specification<T> spec;
+	private final @Nullable Specification<T> spec;
 
 	/**
 	 * Creates a new {@link Specifications} wrapper for the given {@link Specification}.
 	 *
 	 * @param spec can be {@literal null}.
 	 */
-	Specifications(Specification<T> spec) {
+	Specifications(@Nullable Specification<T> spec) {
 		this.spec = spec;
 	}
 
@@ -57,7 +61,7 @@ public class Specifications<T> implements Specification<T>, Serializable {
 	 * @return
 	 */
 	@Deprecated
-	public static <T> Specifications<T> where(Specification<T> spec) {
+	public static <T> Specifications<T> where(@Nullable Specification<T> spec) {
 		return new Specifications<>(spec);
 	}
 
@@ -70,7 +74,7 @@ public class Specifications<T> implements Specification<T>, Serializable {
 	 * @return
 	 */
 	@Deprecated
-	public Specifications<T> and(Specification<T> other) {
+	public Specifications<T> and(@Nullable Specification<T> other) {
 		return new Specifications<>(composed(spec, other, AND));
 	}
 
@@ -83,7 +87,7 @@ public class Specifications<T> implements Specification<T>, Serializable {
 	 * @return
 	 */
 	@Deprecated
-	public Specifications<T> or(Specification<T> other) {
+	public Specifications<T> or(@Nullable Specification<T> other) {
 		return new Specifications<>(composed(spec, other, OR));
 	}
 
@@ -96,7 +100,7 @@ public class Specifications<T> implements Specification<T>, Serializable {
 	 * @return
 	 */
 	@Deprecated
-	public static <T> Specifications<T> not(Specification<T> spec) {
+	public static <T> Specifications<T> not(@Nullable Specification<T> spec) {
 		return new Specifications<>(negated(spec));
 	}
 
@@ -104,6 +108,7 @@ public class Specifications<T> implements Specification<T>, Serializable {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.domain.Specification#toPredicate(javax.persistence.criteria.Root, javax.persistence.criteria.CriteriaQuery, javax.persistence.criteria.CriteriaBuilder)
 	 */
+	@Nullable
 	public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
 		return spec == null ? null : spec.toPredicate(root, query, builder);
 	}
@@ -133,11 +138,11 @@ public class Specifications<T> implements Specification<T>, Serializable {
 		abstract Predicate combine(CriteriaBuilder builder, Predicate lhs, Predicate rhs);
 	}
 
-	static <T> Specification<T> negated(Specification<T> spec) {
+	static <T> Specification<T> negated(@Nullable Specification<T> spec) {
 		return (root, query, builder) -> spec == null ? null : builder.not(spec.toPredicate(root, query, builder));
 	}
 
-	static <T> Specification<T> composed(Specification<T> lhs, Specification<T> rhs, CompositionType compositionType) {
+	static <T> Specification<T> composed(@Nullable Specification<T> lhs, @Nullable Specification<T> rhs, CompositionType compositionType) {
 
 		return (root, query, builder) -> {
 
diff --git a/src/main/java/org/springframework/data/jpa/domain/package-info.java b/src/main/java/org/springframework/data/jpa/domain/package-info.java
index 996a45bc8..67a99500a 100644
--- a/src/main/java/org/springframework/data/jpa/domain/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/domain/package-info.java
@@ -1,5 +1,7 @@
 /**
  * JPA specific support classes to implement domain classes. 
  */
+@NonNullApi
 package org.springframework.data.jpa.domain;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/domain/support/AuditingEntityListener.java b/src/main/java/org/springframework/data/jpa/domain/support/AuditingEntityListener.java
index d53d2dbc5..f07daab0b 100644
--- a/src/main/java/org/springframework/data/jpa/domain/support/AuditingEntityListener.java
+++ b/src/main/java/org/springframework/data/jpa/domain/support/AuditingEntityListener.java
@@ -22,6 +22,7 @@ import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.beans.factory.annotation.Configurable;
 import org.springframework.data.auditing.AuditingHandler;
 import org.springframework.data.domain.Auditable;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -55,11 +56,12 @@ import org.springframework.util.Assert;
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 @Configurable
 public class AuditingEntityListener {
 
-	private ObjectFactory<AuditingHandler> handler;
+	private @Nullable ObjectFactory<AuditingHandler> handler;
 
 	/**
 	 * Configures the {@link AuditingHandler} to be used to set the current auditor on the domain types touched.
@@ -84,7 +86,11 @@ public class AuditingEntityListener {
 		Assert.notNull(target, "Entity must not be null!");
 
 		if (handler != null) {
-			handler.getObject().markCreated(target);
+
+			AuditingHandler object = handler.getObject();
+			if (object != null) {
+				object.markCreated(target);
+			}
 		}
 	}
 
@@ -100,7 +106,11 @@ public class AuditingEntityListener {
 		Assert.notNull(target, "Entity must not be null!");
 
 		if (handler != null) {
-			handler.getObject().markModified(target);
+
+			AuditingHandler object = handler.getObject();
+			if (object != null) {
+				object.markModified(target);
+			}
 		}
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/domain/support/package-info.java b/src/main/java/org/springframework/data/jpa/domain/support/package-info.java
index 4135d713c..7bbd85d1a 100644
--- a/src/main/java/org/springframework/data/jpa/domain/support/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/domain/support/package-info.java
@@ -1,5 +1,7 @@
 /**
  * Implementation classes for auditing with JPA.
  */
+@NonNullApi
 package org.springframework.data.jpa.domain.support;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/mapping/JpaMetamodelMappingContext.java b/src/main/java/org/springframework/data/jpa/mapping/JpaMetamodelMappingContext.java
index ec6dde0ee..af40de93e 100644
--- a/src/main/java/org/springframework/data/jpa/mapping/JpaMetamodelMappingContext.java
+++ b/src/main/java/org/springframework/data/jpa/mapping/JpaMetamodelMappingContext.java
@@ -26,6 +26,7 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.model.Property;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.util.TypeInformation;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -33,6 +34,7 @@ import org.springframework.util.Assert;
  * 
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.3
  */
 public class JpaMetamodelMappingContext
@@ -73,6 +75,11 @@ public class JpaMetamodelMappingContext
 			SimpleTypeHolder simpleTypeHolder) {
 
 		Metamodel metamodel = getMetamodelFor(owner.getType());
+
+		if (metamodel == null) {
+			throw new IllegalStateException(String.format("Metamodel for %s not available!", owner.getType()));
+		}
+
 		return new JpaPersistentPropertyImpl(metamodel, property, owner, simpleTypeHolder);
 	}
 
@@ -91,6 +98,7 @@ public class JpaMetamodelMappingContext
 	 * @param type
 	 * @return
 	 */
+	@Nullable
 	private Metamodel getMetamodelFor(Class<?> type) {
 
 		for (Metamodel model : models) {
diff --git a/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentEntityImpl.java b/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentEntityImpl.java
index daf93c4cc..1fe23c28f 100644
--- a/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentEntityImpl.java
+++ b/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentEntityImpl.java
@@ -31,6 +31,7 @@ import org.springframework.util.Assert;
  * @author Oliver Gierke
  * @author Greg Turnquist
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.3
  */
 class JpaPersistentEntityImpl<T> extends BasicPersistentEntity<T, JpaPersistentProperty>
@@ -112,7 +113,7 @@ class JpaPersistentEntityImpl<T> extends BasicPersistentEntity<T, JpaPersistentP
 		 * @param bean must not be {@literal null}.
 		 * @param proxyIdAccessor must not be {@literal null}.
 		 */
-		public JpaProxyAwareIdentifierAccessor(JpaPersistentEntity<?> entity, Object bean,
+		JpaProxyAwareIdentifierAccessor(JpaPersistentEntity<?> entity, Object bean,
 				ProxyIdAccessor proxyIdAccessor) {
 
 			super(entity, bean);
diff --git a/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImpl.java b/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImpl.java
index 2fa61af99..51000b98a 100644
--- a/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImpl.java
+++ b/src/main/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImpl.java
@@ -47,6 +47,7 @@ import org.springframework.data.mapping.model.Property;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -55,6 +56,7 @@ import org.springframework.util.Assert;
  * @author Oliver Gierke
  * @author Greg Turnquist
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.3
  */
 class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPersistentProperty>
@@ -88,8 +90,8 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 		UPDATEABLE_ANNOTATIONS = Collections.unmodifiableSet(annotations);
 	}
 
-	private final Boolean usePropertyAccess;
-	private final TypeInformation<?> associationTargetType;
+	private final @Nullable Boolean usePropertyAccess;
+	private final @Nullable TypeInformation<?> associationTargetType;
 	private final boolean updateable;
 	private final JpaMetamodel metamodel;
 
@@ -220,6 +222,7 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 	 * 
 	 * @return
 	 */
+	@Nullable
 	private Boolean detectPropertyAccess() {
 
 		org.springframework.data.annotation.AccessType accessType = findAnnotation(
@@ -255,6 +258,7 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 	 * 
 	 * @return
 	 */
+	@Nullable
 	private TypeInformation<?> detectAssociationTargetType() {
 
 		if (!isAssociation()) {
@@ -287,7 +291,7 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 	 * 
 	 * @return
 	 */
-	private final boolean detectUpdatability() {
+	private boolean detectUpdatability() {
 
 		for (Class<? extends Annotation> annotationType : UPDATEABLE_ANNOTATIONS) {
 
diff --git a/src/main/java/org/springframework/data/jpa/mapping/package-info.java b/src/main/java/org/springframework/data/jpa/mapping/package-info.java
index 9df14027a..918ef4b44 100644
--- a/src/main/java/org/springframework/data/jpa/mapping/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/mapping/package-info.java
@@ -1,5 +1,7 @@
 /**
  * JPA specific support classes for the Spring Data mapping subsystem. 
  */
+@NonNullApi
 package org.springframework.data.jpa.mapping;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/provider/HibernateUtils.java b/src/main/java/org/springframework/data/jpa/provider/HibernateUtils.java
index a5062f699..7899a4743 100644
--- a/src/main/java/org/springframework/data/jpa/provider/HibernateUtils.java
+++ b/src/main/java/org/springframework/data/jpa/provider/HibernateUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import org.hibernate.Query;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
@@ -27,6 +28,8 @@ import org.springframework.util.ReflectionUtils;
  * Utility functions to work with Hibernate. Mostly using reflection to make sure common functionality can be executed
  * against all the Hibernate version we support.
  * 
+ * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 1.10.2
  * @soundtrack Benny Greb - Soulfood (Live, https://www.youtube.com/watch?v=9_ErMa_CtSw)
  */
@@ -34,10 +37,9 @@ public abstract class HibernateUtils {
 
 	private static final List<String> TYPES = Arrays.asList("org.hibernate.jpa.HibernateQuery",
 			"org.hibernate.ejb.HibernateQuery");
-	private static final Method GET_HIBERNATE_QUERY;
-
-	private static final Class<?> HIBERNATE_QUERY_INTERFACE;
-	private static final Method QUERY_STRING_METHOD;
+	private static final @Nullable Method GET_HIBERNATE_QUERY;
+	private static final @Nullable Class<?> HIBERNATE_QUERY_INTERFACE;
+	private static final @Nullable Method QUERY_STRING_METHOD;
 
 	private HibernateUtils() {}
 
@@ -73,6 +75,7 @@ public abstract class HibernateUtils {
 	 * @param query
 	 * @return
 	 */
+	@Nullable
 	public static String getHibernateQuery(Object query) {
 
 		if (HIBERNATE_QUERY_INTERFACE != null && QUERY_STRING_METHOD != null
@@ -84,6 +87,12 @@ public abstract class HibernateUtils {
 			query = ((javax.persistence.Query) query).unwrap(HIBERNATE_QUERY_INTERFACE);
 		}
 
-		return ((Query) ReflectionUtils.invokeMethod(GET_HIBERNATE_QUERY, query)).getQueryString();
+		if (GET_HIBERNATE_QUERY == null) {
+			throw new IllegalStateException(
+					"Cannot invoke getHibernateQuery(…). No underlying method for a reflective call found.");
+		}
+
+		Query q = (Query) ReflectionUtils.invokeMethod(GET_HIBERNATE_QUERY, query);
+		return q == null ? "" : q.getQueryString();
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java b/src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java
index bbfafc30b..f86ce6949 100644
--- a/src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java
+++ b/src/main/java/org/springframework/data/jpa/provider/PersistenceProvider.java
@@ -21,6 +21,7 @@ import static org.springframework.data.jpa.provider.PersistenceProvider.Constant
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.NoSuchElementException;
 
 import javax.persistence.EntityManager;
 import javax.persistence.Query;
@@ -32,6 +33,7 @@ import org.hibernate.ScrollMode;
 import org.hibernate.ScrollableResults;
 import org.hibernate.proxy.HibernateProxy;
 import org.springframework.data.util.CloseableIterator;
+import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.util.Assert;
 import org.springframework.util.ConcurrentReferenceHashMap;
@@ -41,6 +43,7 @@ import org.springframework.util.ConcurrentReferenceHashMap;
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 
@@ -94,8 +97,9 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.provider.PersistenceProvider#potentiallyConvertEmptyCollection(java.util.Collection)
 		 */
+		@Nullable
 		@Override
-		public <T> Collection<T> potentiallyConvertEmptyCollection(Collection<T> collection) {
+		public <T> Collection<T> potentiallyConvertEmptyCollection(@Nullable Collection<T> collection) {
 			return collection == null || collection.isEmpty() ? null : collection;
 		}
 
@@ -132,6 +136,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.repository.support.ProxyIdAccessor#getIdentifierFrom(java.lang.Object)
 		 */
+		@Nullable
 		@Override
 		public Object getIdentifierFrom(Object entity) {
 			return null;
@@ -140,8 +145,9 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		/* (non-Javadoc)
 		 * @see org.springframework.data.jpa.provider.PersistenceProvider#potentiallyConvertEmptyCollection(java.util.Collection)
 		 */
+		@Nullable
 		@Override
-		public <T> Collection<T> potentiallyConvertEmptyCollection(Collection<T> collection) {
+		public <T> Collection<T> potentiallyConvertEmptyCollection(@Nullable Collection<T> collection) {
 			return collection == null || collection.isEmpty() ? null : collection;
 		}
 
@@ -164,6 +170,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.repository.query.QueryExtractor#extractQueryString(javax.persistence.Query)
 		 */
+		@Nullable
 		@Override
 		public String extractQueryString(Query query) {
 			return null;
@@ -191,6 +198,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.repository.support.ProxyIdAccessor#getIdentifierFrom(java.lang.Object)
 		 */
+		@Nullable
 		@Override
 		public Object getIdentifierFrom(Object entity) {
 			return null;
@@ -331,7 +339,8 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 	 * @param collection
 	 * @return
 	 */
-	public <T> Collection<T> potentiallyConvertEmptyCollection(Collection<T> collection) {
+	@Nullable
+	public <T> Collection<T> potentiallyConvertEmptyCollection(@Nullable Collection<T> collection) {
 		return collection;
 	}
 
@@ -350,7 +359,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 	 */
 	private static class HibernateScrollableResultsIterator implements CloseableIterator<Object> {
 
-		private final ScrollableResults scrollableResults;
+		private final @Nullable ScrollableResults scrollableResults;
 
 		/**
 		 * Creates a new {@link HibernateScrollableResultsIterator} for the given {@link Query}.
@@ -371,6 +380,10 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		@Override
 		public Object next() {
 
+			if (scrollableResults == null) {
+				throw new NoSuchElementException("No ScrollableResults");
+			}
+
 			Object[] row = scrollableResults.get();
 
 			return row.length == 1 ? row[0] : row;
@@ -382,7 +395,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 */
 		@Override
 		public boolean hasNext() {
-			return scrollableResults == null ? false : scrollableResults.next();
+			return scrollableResults != null && scrollableResults.next();
 		}
 
 		/*
@@ -409,7 +422,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 	@SuppressWarnings("unchecked")
 	private static class EclipseLinkScrollableResultsIterator<T> implements CloseableIterator<T> {
 
-		private final ScrollableCursor scrollableCursor;
+		private final @Nullable ScrollableCursor scrollableCursor;
 
 		/**
 		 * Creates a new {@link EclipseLinkScrollableResultsIterator} for the given JPA {@link Query}.
@@ -429,7 +442,7 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 */
 		@Override
 		public boolean hasNext() {
-			return scrollableCursor == null ? false : scrollableCursor.hasNext();
+			return scrollableCursor != null && scrollableCursor.hasNext();
 		}
 
 		/*
@@ -438,6 +451,11 @@ public enum PersistenceProvider implements QueryExtractor, ProxyIdAccessor {
 		 */
 		@Override
 		public T next() {
+
+			if (scrollableCursor == null) {
+				throw new NoSuchElementException("No ScrollableCursor");
+			}
+
 			return (T) scrollableCursor.next();
 		}
 
diff --git a/src/main/java/org/springframework/data/jpa/provider/ProxyIdAccessor.java b/src/main/java/org/springframework/data/jpa/provider/ProxyIdAccessor.java
index 4a319662d..98baccd0a 100644
--- a/src/main/java/org/springframework/data/jpa/provider/ProxyIdAccessor.java
+++ b/src/main/java/org/springframework/data/jpa/provider/ProxyIdAccessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,10 +15,13 @@
  */
 package org.springframework.data.jpa.provider;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Interface for a persistence provider specific accessor of identifiers held in proxies.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  */
 public interface ProxyIdAccessor {
 
@@ -37,5 +40,6 @@ public interface ProxyIdAccessor {
 	 * @param entity must not be {@literal null}.
 	 * @return
 	 */
+	@Nullable
 	Object getIdentifierFrom(Object entity);
 }
diff --git a/src/main/java/org/springframework/data/jpa/provider/QueryExtractor.java b/src/main/java/org/springframework/data/jpa/provider/QueryExtractor.java
index 244b5531a..c8fe9080c 100644
--- a/src/main/java/org/springframework/data/jpa/provider/QueryExtractor.java
+++ b/src/main/java/org/springframework/data/jpa/provider/QueryExtractor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2011 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,10 +17,13 @@ package org.springframework.data.jpa.provider;
 
 import javax.persistence.Query;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Interface to hide different implementations to extract the original JPA query string from a {@link Query}.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  */
 public interface QueryExtractor {
 
@@ -31,6 +34,7 @@ public interface QueryExtractor {
 	 * @param query
 	 * @return the query string representing the query or {@literal null} if resolving is not possible.
 	 */
+	@Nullable
 	String extractQueryString(Query query);
 
 	/**
diff --git a/src/main/java/org/springframework/data/jpa/provider/package-info.java b/src/main/java/org/springframework/data/jpa/provider/package-info.java
new file mode 100644
index 000000000..39a8e1ef9
--- /dev/null
+++ b/src/main/java/org/springframework/data/jpa/provider/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * JPA provider-specific utilities.
+ */
+@NonNullApi
+package org.springframework.data.jpa.provider;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/repository/JpaSpecificationExecutor.java b/src/main/java/org/springframework/data/jpa/repository/JpaSpecificationExecutor.java
index 40b001320..e647519b8 100644
--- a/src/main/java/org/springframework/data/jpa/repository/JpaSpecificationExecutor.java
+++ b/src/main/java/org/springframework/data/jpa/repository/JpaSpecificationExecutor.java
@@ -22,6 +22,7 @@ import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.domain.Specification;
+import org.springframework.lang.Nullable;
 
 /**
  * Interface to allow execution of {@link Specification}s based on the JPA criteria API.
@@ -38,7 +39,7 @@ public interface JpaSpecificationExecutor<T> {
 	 * @return never {@literal null}.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one entity found.
 	 */
-	Optional<T> findOne(Specification<T> spec);
+	Optional<T> findOne(@Nullable Specification<T> spec);
 
 	/**
 	 * Returns all entities matching the given {@link Specification}.
@@ -46,25 +47,25 @@ public interface JpaSpecificationExecutor<T> {
 	 * @param spec can be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	List<T> findAll(Specification<T> spec);
+	List<T> findAll(@Nullable Specification<T> spec);
 
 	/**
 	 * Returns a {@link Page} of entities matching the given {@link Specification}.
 	 *
 	 * @param spec can be {@literal null}.
-	 * @param pageable can be {@literal null}.
+	 * @param pageable must not be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	Page<T> findAll(Specification<T> spec, Pageable pageable);
+	Page<T> findAll(@Nullable Specification<T> spec, Pageable pageable);
 
 	/**
 	 * Returns all entities matching the given {@link Specification} and {@link Sort}.
 	 *
 	 * @param spec can be {@literal null}.
-	 * @param sort can be {@literal null}.
+	 * @param sort must not be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	List<T> findAll(Specification<T> spec, Sort sort);
+	List<T> findAll(@Nullable Specification<T> spec, Sort sort);
 
 	/**
 	 * Returns the number of instances that the given {@link Specification} will return.
@@ -72,5 +73,5 @@ public interface JpaSpecificationExecutor<T> {
 	 * @param spec the {@link Specification} to count instances for. Can be {@literal null}.
 	 * @return the number of instances.
 	 */
-	long count(Specification<T> spec);
+	long count(@Nullable Specification<T> spec);
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryBean.java b/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryBean.java
index e86107411..3d721c43c 100644
--- a/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryBean.java
+++ b/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryBean.java
@@ -49,7 +49,7 @@ class JpaRepositoryBean<T> extends CdiRepositoryBean<T> {
 	 * @param entityManagerBean must not be {@literal null}.
 	 * @param qualifiers must not be {@literal null}.
 	 * @param repositoryType must not be {@literal null}.
-	 * @param detector can be {@literal null}.
+	 * @param detector can be {@link Optional#empty()}.
 	 */
 	JpaRepositoryBean(BeanManager beanManager, Bean<EntityManager> entityManagerBean, Set<Annotation> qualifiers,
 			Class<T> repositoryType, Optional<CustomRepositoryImplementationDetector> detector) {
diff --git a/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryExtension.java b/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryExtension.java
index cc4656573..fd22e1636 100644
--- a/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryExtension.java
+++ b/src/main/java/org/springframework/data/jpa/repository/cdi/JpaRepositoryExtension.java
@@ -123,6 +123,6 @@ public class JpaRepositoryExtension extends CdiRepositoryExtensionSupport {
 
 		// Construct and return the repository bean.
 		return new JpaRepositoryBean<T>(beanManager, entityManagerBean, qualifiers, repositoryType,
-				Optional.ofNullable(getCustomImplementationDetector()));
+				Optional.of(getCustomImplementationDetector()));
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/cdi/package-info.java b/src/main/java/org/springframework/data/jpa/repository/cdi/package-info.java
index 9c7fadf17..2b6788bd0 100644
--- a/src/main/java/org/springframework/data/jpa/repository/cdi/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/repository/cdi/package-info.java
@@ -1,5 +1,7 @@
 /**
  * CDI support for Spring Data JPA Repositories. 
  */
+@NonNullApi
 package org.springframework.data.jpa.repository.cdi;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/repository/config/JpaMetamodelMappingContextFactoryBean.java b/src/main/java/org/springframework/data/jpa/repository/config/JpaMetamodelMappingContextFactoryBean.java
index a12e1f2bc..fd6c42164 100644
--- a/src/main/java/org/springframework/data/jpa/repository/config/JpaMetamodelMappingContextFactoryBean.java
+++ b/src/main/java/org/springframework/data/jpa/repository/config/JpaMetamodelMappingContextFactoryBean.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright 2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.springframework.data.jpa.repository.config;
 
 import java.util.Collection;
@@ -16,17 +31,19 @@ import org.springframework.beans.factory.config.AbstractFactoryBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.data.jpa.mapping.JpaMetamodelMappingContext;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link FactoryBean} to setup {@link JpaMetamodelMappingContext} instances from Spring configuration.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 1.6
  */
-class JpaMetamodelMappingContextFactoryBean extends AbstractFactoryBean<JpaMetamodelMappingContext> implements
-		ApplicationContextAware {
+class JpaMetamodelMappingContextFactoryBean extends AbstractFactoryBean<JpaMetamodelMappingContext>
+		implements ApplicationContextAware {
 
-	private ListableBeanFactory beanFactory;
+	private @Nullable ListableBeanFactory beanFactory;
 
 	/* 
 	 * (non-Javadoc)
@@ -82,8 +99,12 @@ class JpaMetamodelMappingContextFactoryBean extends AbstractFactoryBean<JpaMetam
 	 */
 	private Set<Metamodel> getMetamodels() {
 
-		Collection<EntityManagerFactory> factories = BeanFactoryUtils.beansOfTypeIncludingAncestors(beanFactory,
-				EntityManagerFactory.class).values();
+		if (beanFactory == null) {
+			throw new IllegalStateException("BeanFactory must not be null!");
+		}
+
+		Collection<EntityManagerFactory> factories = BeanFactoryUtils
+				.beansOfTypeIncludingAncestors(beanFactory, EntityManagerFactory.class).values();
 		Set<Metamodel> metamodels = new HashSet<Metamodel>(factories.size());
 
 		for (EntityManagerFactory emf : factories) {
diff --git a/src/main/java/org/springframework/data/jpa/repository/config/JpaRepositoryConfigExtension.java b/src/main/java/org/springframework/data/jpa/repository/config/JpaRepositoryConfigExtension.java
index 44fd91a2b..fbbe958ca 100644
--- a/src/main/java/org/springframework/data/jpa/repository/config/JpaRepositoryConfigExtension.java
+++ b/src/main/java/org/springframework/data/jpa/repository/config/JpaRepositoryConfigExtension.java
@@ -55,12 +55,13 @@ import org.springframework.util.StringUtils;
  * {@link PersistenceUnit} annotated properties and methods) as well as
  * {@link PersistenceExceptionTranslationPostProcessor} to enable exception translation of persistence specific
  * exceptions into Spring's {@link DataAccessException} hierarchy.
- * 
+ *
  * @author Oliver Gierke
  * @author Eberhard Wolff
  * @author Gil Markham
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensionSupport {
 
@@ -68,7 +69,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 	private static final String DEFAULT_TRANSACTION_MANAGER_BEAN_NAME = "transactionManager";
 	private static final String ENABLE_DEFAULT_TRANSACTIONS_ATTRIBUTE = "enableDefaultTransactions";
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#getModuleName()
 	 */
@@ -86,7 +87,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		return JpaRepositoryFactoryBean.class.getName();
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config14.RepositoryConfigurationExtensionSupport#getModulePrefix()
 	 */
@@ -95,7 +96,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		return getModuleName().toLowerCase(Locale.US);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#getIdentifyingAnnotations()
 	 */
@@ -104,7 +105,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		return Arrays.asList(Entity.class, MappedSuperclass.class);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#getIdentifyingTypes()
 	 */
@@ -113,7 +114,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		return Collections.<Class<?>> singleton(JpaRepository.class);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#postProcess(org.springframework.beans.factory.support.BeanDefinitionBuilder, org.springframework.data.repository.config.RepositoryConfigurationSource)
 	 */
@@ -126,7 +127,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		builder.addPropertyReference("mappingContext", JPA_MAPPING_CONTEXT_BEAN_NAME);
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#postProcess(org.springframework.beans.factory.support.BeanDefinitionBuilder, org.springframework.data.repository.config.AnnotationRepositoryConfigurationSource)
 	 */
@@ -139,7 +140,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 				attributes.getBoolean(ENABLE_DEFAULT_TRANSACTIONS_ATTRIBUTE));
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#postProcess(org.springframework.beans.factory.support.BeanDefinitionBuilder, org.springframework.data.repository.config.XmlRepositoryConfigurationSource)
 	 */
@@ -153,7 +154,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 		}
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.config.RepositoryConfigurationExtensionSupport#registerBeansForRoot(org.springframework.beans.factory.support.BeanDefinitionRegistry, org.springframework.data.repository.config.RepositoryConfigurationSource)
 	 */
@@ -184,7 +185,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 	/**
 	 * Creates an anonymous factory to extract the actual {@link javax.persistence.EntityManager} from the
 	 * {@link javax.persistence.EntityManagerFactory} bean name reference.
-	 * 
+	 *
 	 * @param config
 	 * @param source
 	 * @return
@@ -205,8 +206,7 @@ public class JpaRepositoryConfigExtension extends RepositoryConfigurationExtensi
 
 	private static String getEntityManagerBeanRef(RepositoryConfigurationSource config) {
 
-		Optional<String> entityManagerFactoryRef = config == null ? Optional.empty()
-				: config.getAttribute("entityManagerFactoryRef");
+		Optional<String> entityManagerFactoryRef = config.getAttribute("entityManagerFactoryRef");
 		return entityManagerFactoryRef.orElse("entityManagerFactory");
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/config/package-info.java b/src/main/java/org/springframework/data/jpa/repository/config/package-info.java
index 9af11c562..d70b4fa53 100644
--- a/src/main/java/org/springframework/data/jpa/repository/config/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/repository/config/package-info.java
@@ -1,5 +1,7 @@
 /**
  * Classes for JPA namespace configuration.
  */
+@NonNullApi
 package org.springframework.data.jpa.repository.config;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/repository/package-info.java b/src/main/java/org/springframework/data/jpa/repository/package-info.java
index 814dc765a..c27c800cb 100644
--- a/src/main/java/org/springframework/data/jpa/repository/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/repository/package-info.java
@@ -1,5 +1,7 @@
 /**
  * Interfaces and annotations for JPA specific repositories.
  */
+@NonNullApi
 package org.springframework.data.jpa.repository;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java
index 05f35588e..8bd844377 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java
@@ -42,11 +42,12 @@ import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.data.util.Lazy;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
  * Abstract base class to implement {@link RepositoryQuery}s.
- * 
+ *
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Mark Paluch
@@ -63,7 +64,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Creates a new {@link AbstractJpaQuery} from the given {@link JpaQueryMethod}.
-	 * 
+	 *
 	 * @param method
 	 * @param em
 	 */
@@ -81,13 +82,14 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.query.RepositoryQuery#getQueryMethod()
 	 */
+	@Override
 	public JpaQueryMethod getQueryMethod() {
 		return method;
 	}
 
 	/**
 	 * Returns the {@link EntityManager}.
-	 * 
+	 *
 	 * @return will never be {@literal null}.
 	 */
 	protected EntityManager getEntityManager() {
@@ -96,7 +98,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Returns the {@link JpaMetamodel}.
-	 * 
+	 *
 	 * @return
 	 */
 	protected JpaMetamodel getMetamodel() {
@@ -107,6 +109,8 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.query.RepositoryQuery#execute(java.lang.Object[])
 	 */
+	@Nullable
+	@Override
 	public Object execute(Object[] parameters) {
 		return doExecute(getExecution(), parameters);
 	}
@@ -116,6 +120,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 	 * @param values
 	 * @return
 	 */
+	@Nullable
 	private Object doExecute(JpaQueryExecution execution, Object[] values) {
 
 		Object result = execution.execute(this, values);
@@ -147,7 +152,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Applies the declared query hints to the given query.
-	 * 
+	 *
 	 * @param query
 	 * @return
 	 */
@@ -162,7 +167,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Protected to be able to customize in sub-classes.
-	 * 
+	 *
 	 * @param query must not be {@literal null}.
 	 * @param hint must not be {@literal null}.
 	 */
@@ -176,7 +181,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Applies the {@link LockModeType} provided by the {@link JpaQueryMethod} to the given {@link Query}.
-	 * 
+	 *
 	 * @param query must not be {@literal null}.
 	 * @param method must not be {@literal null}.
 	 * @return
@@ -198,7 +203,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 	/**
 	 * Configures the {@link javax.persistence.EntityGraph} to use for the given {@link JpaQueryMethod} if the
 	 * {@link EntityGraph} annotation is present.
-	 * 
+	 *
 	 * @param query must not be {@literal null}.
 	 * @param method must not be {@literal null}.
 	 * @return
@@ -225,7 +230,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Creates a {@link Query} instance for the given values.
-	 * 
+	 *
 	 * @param values must not be {@literal null}.
 	 * @return
 	 */
@@ -233,7 +238,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 	/**
 	 * Creates a {@link TypedQuery} for counting using the given values.
-	 * 
+	 *
 	 * @param values must not be {@literal null}.
 	 * @return
 	 */
@@ -245,7 +250,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 
 		/**
 		 * Creates a new {@link TupleConverter} for the given {@link ReturnedType}.
-		 * 
+		 *
 		 * @param type must not be {@literal null}.
 		 */
 		public TupleConverter(ReturnedType type) {
@@ -255,7 +260,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 			this.type = type;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
 		 */
@@ -267,7 +272,7 @@ public abstract class AbstractJpaQuery implements RepositoryQuery {
 			}
 
 			Tuple tuple = (Tuple) source;
-			Map<String, Object> result = new HashMap<String, Object>();
+			Map<String, Object> result = new HashMap<>();
 			List<TupleElement<?>> elements = tuple.getElements();
 
 			if (elements.size() == 1) {
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/DefaultJpaEntityMetadata.java b/src/main/java/org/springframework/data/jpa/repository/query/DefaultJpaEntityMetadata.java
index 75685eaa8..388c7f047 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/DefaultJpaEntityMetadata.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/DefaultJpaEntityMetadata.java
@@ -23,7 +23,7 @@ import org.springframework.util.StringUtils;
 
 /**
  * Default implementation for {@link JpaEntityMetadata}.
- * 
+ *
  * @author Oliver Gierke
  * @author Christoph Strobl
  */
@@ -33,7 +33,7 @@ public class DefaultJpaEntityMetadata<T> implements JpaEntityMetadata<T> {
 
 	/**
 	 * Creates a new {@link DefaultJpaEntityMetadata} for the given domain type.
-	 * 
+	 *
 	 * @param domainType must not be {@literal null}.
 	 */
 	public DefaultJpaEntityMetadata(Class<T> domainType) {
@@ -42,7 +42,7 @@ public class DefaultJpaEntityMetadata<T> implements JpaEntityMetadata<T> {
 		this.domainType = domainType;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.core.EntityMetadata#getJavaType()
 	 */
@@ -55,11 +55,10 @@ public class DefaultJpaEntityMetadata<T> implements JpaEntityMetadata<T> {
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.support.JpaEntityMetadata#getEntityName()
 	 */
+	@Override
 	public String getEntityName() {
 
 		Entity entity = AnnotatedElementUtils.findMergedAnnotation(domainType, Entity.class);
-		boolean hasName = null != entity && StringUtils.hasText(entity.name());
-
-		return hasName ? entity.name() : domainType.getSimpleName();
+		return null != entity && StringUtils.hasText(entity.name()) ? entity.name() : domainType.getSimpleName();
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/Jpa21Utils.java b/src/main/java/org/springframework/data/jpa/repository/query/Jpa21Utils.java
index c794a0f1d..1550ed1eb 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/Jpa21Utils.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/Jpa21Utils.java
@@ -27,6 +27,7 @@ import javax.persistence.EntityManager;
 import javax.persistence.Query;
 import javax.persistence.Subgraph;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
@@ -39,11 +40,12 @@ import org.springframework.util.StringUtils;
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.6
  */
 public class Jpa21Utils {
 
-	private static final Method GET_ENTITY_GRAPH_METHOD;
+	private static final @Nullable Method GET_ENTITY_GRAPH_METHOD;
 	private static final boolean JPA21_AVAILABLE = ClassUtils.isPresent("javax.persistence.NamedEntityGraph",
 			Jpa21Utils.class.getClassLoader());
 
@@ -69,7 +71,7 @@ public class Jpa21Utils {
 	 * @return a {@code Map} with the hints or an empty {@code Map} if no hints were found.
 	 * @since 1.8
 	 */
-	public static Map<String, Object> tryGetFetchGraphHints(EntityManager em, JpaEntityGraph entityGraph,
+	public static Map<String, Object> tryGetFetchGraphHints(EntityManager em, @Nullable JpaEntityGraph entityGraph,
 			Class<?> entityType) {
 
 		if (entityGraph == null) {
@@ -95,6 +97,7 @@ public class Jpa21Utils {
 	 * @param entityType must not be {@literal null}.
 	 * @return the {@link EntityGraph} described by the given {@code entityGraph}.
 	 */
+	@Nullable
 	private static EntityGraph<?> tryGetFetchGraph(EntityManager em, JpaEntityGraph jpaEntityGraph, Class<?> entityType) {
 
 		Assert.notNull(em, "EntityManager must not be null!");
@@ -157,7 +160,8 @@ public class Jpa21Utils {
 		}
 	}
 
-	private static void createGraph(String[] pathComponents, int offset, EntityGraph<?> root, Subgraph<?> parent) {
+	private static void createGraph(String[] pathComponents, int offset, EntityGraph<?> root,
+			@Nullable Subgraph<?> parent) {
 
 		String attributeName = pathComponents[offset];
 
@@ -216,8 +220,9 @@ public class Jpa21Utils {
 	 * @param parent
 	 * @return {@literal null} if not found.
 	 */
+	@Nullable
 	private static AttributeNode<?> findAttributeNode(String attributeNodeName, EntityGraph<?> entityGraph,
-			Subgraph<?> parent) {
+			@Nullable Subgraph<?> parent) {
 		return findAttributeNode(attributeNodeName,
 				parent != null ? parent.getAttributeNodes() : entityGraph.getAttributeNodes());
 	}
@@ -230,6 +235,7 @@ public class Jpa21Utils {
 	 * @param nodes
 	 * @return {@literal null} if not found.
 	 */
+	@Nullable
 	private static AttributeNode<?> findAttributeNode(String attributeNodeName, List<AttributeNode<?>> nodes) {
 
 		for (AttributeNode<?> node : nodes) {
@@ -249,6 +255,7 @@ public class Jpa21Utils {
 	 * @param node
 	 * @return
 	 */
+	@Nullable
 	private static Subgraph<?> getSubgraph(AttributeNode<?> node) {
 		return node.getSubgraphs().isEmpty() ? null : node.getSubgraphs().values().iterator().next();
 	}
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaCountQueryCreator.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaCountQueryCreator.java
index bbbddb90a..6abf48376 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaCountQueryCreator.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaCountQueryCreator.java
@@ -24,12 +24,14 @@ import javax.persistence.criteria.Root;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.data.repository.query.parser.PartTree;
+import org.springframework.lang.Nullable;
 
 /**
  * Special {@link JpaQueryCreator} that creates a count projecting query.
  * 
  * @author Oliver Gierke
  * @author Marc Lefrançois
+ * @author Mark Paluch
  */
 public class JpaCountQueryCreator extends JpaQueryCreator {
 
@@ -61,7 +63,7 @@ public class JpaCountQueryCreator extends JpaQueryCreator {
 	 */
 	@Override
 	@SuppressWarnings("unchecked")
-	protected CriteriaQuery<? extends Object> complete(Predicate predicate, Sort sort,
+	protected CriteriaQuery<? extends Object> complete(@Nullable Predicate predicate, Sort sort,
 			CriteriaQuery<? extends Object> query, CriteriaBuilder builder, Root<?> root) {
 
 		CriteriaQuery<? extends Object> select = query.select(getCountQuery(query, builder, root));
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaEntityGraph.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaEntityGraph.java
index f442330da..b4968645d 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaEntityGraph.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaEntityGraph.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.List;
 
 import org.springframework.data.jpa.repository.EntityGraph;
 import org.springframework.data.jpa.repository.EntityGraph.EntityGraphType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -27,6 +28,7 @@ import org.springframework.util.StringUtils;
  * EntityGraph configuration for JPA 2.1 {@link EntityGraph}s.
  * 
  * @author Thomas Darimont
+ * @author Mark Paluch
  * @since 1.6
  */
 public class JpaEntityGraph {
@@ -56,7 +58,7 @@ public class JpaEntityGraph {
 	 * @param attributePaths may be {@literal null}.
 	 * @since 1.9
 	 */
-	public JpaEntityGraph(String name, EntityGraphType type, String[] attributePaths) {
+	public JpaEntityGraph(String name, EntityGraphType type, @Nullable String[] attributePaths) {
 
 		Assert.hasText(name, "The name of an EntityGraph must not be null or empty!");
 		Assert.notNull(type, "FetchGraphType must not be null!");
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaParameters.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaParameters.java
index fc3915bf6..d7a8e71cb 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaParameters.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaParameters.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,11 +26,13 @@ import org.springframework.data.jpa.repository.Temporal;
 import org.springframework.data.jpa.repository.query.JpaParameters.JpaParameter;
 import org.springframework.data.repository.query.Parameter;
 import org.springframework.data.repository.query.Parameters;
+import org.springframework.lang.Nullable;
 
 /**
  * Custom extension of {@link Parameters} discovering additional query parameter annotations.
  * 
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public class JpaParameters extends Parameters<JpaParameters, JpaParameter> {
 
@@ -73,8 +75,8 @@ public class JpaParameters extends Parameters<JpaParameters, JpaParameter> {
 	 */
 	static class JpaParameter extends Parameter {
 
-		private final Temporal annotation;
-		private TemporalType temporalType;
+		private final @Nullable Temporal annotation;
+		private @Nullable TemporalType temporalType;
 
 		/**
 		 * Creates a new {@link JpaParameter}.
@@ -89,8 +91,8 @@ public class JpaParameters extends Parameters<JpaParameters, JpaParameter> {
 			this.temporalType = null;
 
 			if (!isDateParameter() && hasTemporalParamAnnotation()) {
-				throw new IllegalArgumentException(Temporal.class.getSimpleName()
-						+ " annotation is only allowed on Date parameter!");
+				throw new IllegalArgumentException(
+						Temporal.class.getSimpleName() + " annotation is only allowed on Date parameter!");
 			}
 		}
 
@@ -106,14 +108,15 @@ public class JpaParameters extends Parameters<JpaParameters, JpaParameter> {
 		/**
 		 * @return {@literal true} if this parameter is of type {@link Date} and has an {@link Temporal} annotation.
 		 */
-		public boolean isTemporalParameter() {
+		boolean isTemporalParameter() {
 			return isDateParameter() && hasTemporalParamAnnotation();
 		}
 
 		/**
 		 * @return the {@link TemporalType} on the {@link Temporal} annotation of the given {@link Parameter}.
 		 */
-		public TemporalType getTemporalType() {
+		@Nullable
+		TemporalType getTemporalType() {
 
 			if (temporalType == null) {
 				this.temporalType = annotation == null ? null : annotation.value();
@@ -122,6 +125,22 @@ public class JpaParameters extends Parameters<JpaParameters, JpaParameter> {
 			return this.temporalType;
 		}
 
+		/**
+		 * @return the required {@link TemporalType} on the {@link Temporal} annotation of the given {@link Parameter}.
+		 * @throws IllegalStateException if the parameter does not define a {@link TemporalType}.
+		 * @since 2.0
+		 */
+		TemporalType getRequiredTemporalType() throws IllegalStateException {
+
+			TemporalType temporalType = getTemporalType();
+
+			if (temporalType != null) {
+				return temporalType;
+			}
+
+			throw new IllegalStateException(String.format("Required temporal type not found for %s!", getType()));
+		}
+
 		private boolean hasTemporalParamAnnotation() {
 			return annotation != null;
 		}
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
index b1da74c6d..40bb4184b 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryCreator.java
@@ -42,14 +42,16 @@ import org.springframework.data.repository.query.parser.AbstractQueryCreator;
 import org.springframework.data.repository.query.parser.Part;
 import org.springframework.data.repository.query.parser.Part.Type;
 import org.springframework.data.repository.query.parser.PartTree;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
  * Query creator to create a {@link CriteriaQuery} from a {@link PartTree}.
- * 
+ *
  * @author Oliver Gierke
  * @author Mark Paluch
  * @author Michael Cramer
+ * @author Mark Paluch
  */
 public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extends Object>, Predicate> {
 
@@ -62,7 +64,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 	/**
 	 * Create a new {@link JpaQueryCreator}.
-	 * 
+	 *
 	 * @param tree must not be {@literal null}.
 	 * @param type must not be {@literal null}.
 	 * @param builder must not be {@literal null}.
@@ -85,7 +87,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 	/**
 	 * Creates the {@link CriteriaQuery} to apply predicates on.
-	 * 
+	 *
 	 * @param builder will never be {@literal null}.
 	 * @param type will never be {@literal null}.
 	 * @return must not be {@literal null}.
@@ -100,7 +102,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 	/**
 	 * Returns all {@link javax.persistence.criteria.ParameterExpression} created when creating the query.
-	 * 
+	 *
 	 * @return the parameterExpressions
 	 */
 	public List<ParameterMetadata<?>> getParameterExpressions() {
@@ -148,7 +150,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 	/**
 	 * Template method to finalize the given {@link Predicate} using the given {@link CriteriaQuery} and
 	 * {@link CriteriaBuilder}.
-	 * 
+	 *
 	 * @param predicate
 	 * @param sort
 	 * @param query
@@ -156,12 +158,12 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 	 * @return
 	 */
 	@SuppressWarnings({ "unchecked", "rawtypes" })
-	protected CriteriaQuery<? extends Object> complete(Predicate predicate, Sort sort,
+	protected CriteriaQuery<? extends Object> complete(@Nullable Predicate predicate, Sort sort,
 			CriteriaQuery<? extends Object> query, CriteriaBuilder builder, Root<?> root) {
 
 		if (returnedType.needsCustomConstruction()) {
 
-			List<Selection<?>> selections = new ArrayList<Selection<?>>();
+			List<Selection<?>> selections = new ArrayList<>();
 
 			for (String property : returnedType.getInputProperties()) {
 
@@ -207,7 +209,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 	/**
 	 * Simple builder to contain logic to create JPA {@link Predicate}s from {@link Part}s.
-	 * 
+	 *
 	 * @author Phil Webb
 	 * @author Oliver Gierke
 	 */
@@ -219,7 +221,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 		/**
 		 * Creates a new {@link PredicateBuilder} for the given {@link Part} and {@link Root}.
-		 * 
+		 *
 		 * @param part must not be {@literal null}.
 		 * @param root must not be {@literal null}.
 		 */
@@ -233,7 +235,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 		/**
 		 * Builds a JPA {@link Predicate} from the underlying {@link Part}.
-		 * 
+		 *
 		 * @return
 		 */
 		public Predicate build() {
@@ -331,7 +333,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 		/**
 		 * Applies an {@code UPPERCASE} conversion to the given {@link Expression} in case the underlying {@link Part}
 		 * requires ignoring case.
-		 * 
+		 *
 		 * @param expression must not be {@literal null}.
 		 * @return
 		 */
@@ -364,7 +366,7 @@ public class JpaQueryCreator extends AbstractQueryCreator<CriteriaQuery<? extend
 
 		/**
 		 * Returns a path to a {@link Comparable}.
-		 * 
+		 *
 		 * @param root
 		 * @param part
 		 * @return
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
index 766cca559..058cda486 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
@@ -39,6 +39,7 @@ import org.springframework.data.repository.query.ParametersParameterAccessor;
 import org.springframework.data.repository.support.PageableExecutionUtils;
 import org.springframework.data.util.CloseableIterator;
 import org.springframework.data.util.StreamUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -74,6 +75,7 @@ public abstract class JpaQueryExecution {
 	 * @param values must not be {@literal null}.
 	 * @return
 	 */
+	@Nullable
 	public Object execute(AbstractJpaQuery query, Object[] values) {
 
 		Assert.notNull(query, "AbstractJpaQuery must not be null!");
@@ -109,6 +111,7 @@ public abstract class JpaQueryExecution {
 	 * @param values
 	 * @return
 	 */
+	@Nullable
 	protected abstract Object doExecute(AbstractJpaQuery query, Object[] values);
 
 	/**
@@ -212,7 +215,7 @@ public abstract class JpaQueryExecution {
 	 */
 	static class ModifyingExecution extends JpaQueryExecution {
 
-		private final EntityManager em;
+		private final @Nullable EntityManager em;
 
 		/**
 		 * Creates an execution that automatically clears the given {@link EntityManager} after execution if the given
@@ -220,7 +223,7 @@ public abstract class JpaQueryExecution {
 		 * 
 		 * @param em
 		 */
-		public ModifyingExecution(JpaQueryMethod method, EntityManager em) {
+		public ModifyingExecution(JpaQueryMethod method, @Nullable EntityManager em) {
 
 			Class<?> returnType = method.getReturnType();
 
@@ -363,10 +366,7 @@ public abstract class JpaQueryExecution {
 				Class<?> optionalType = ClassUtils.forName("java.util.Optional", classLoader);
 				conversionService.removeConvertible(Object.class, optionalType);
 
-			} catch (ClassNotFoundException e) {
-				return;
-			} catch (LinkageError e) {
-				return;
+			} catch (ClassNotFoundException | LinkageError o_O) {
 			}
 		}
 	}
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryFactory.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryFactory.java
index 20d2a94ed..9e9b9c8d7 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryFactory.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,11 +24,13 @@ import org.springframework.data.repository.query.EvaluationContextProvider;
 import org.springframework.data.repository.query.QueryMethod;
 import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.lang.Nullable;
 
 /**
  * Factory to create the appropriate {@link RepositoryQuery} for a {@link JpaQueryMethod}.
  * 
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 enum JpaQueryFactory {
 
@@ -46,6 +48,7 @@ enum JpaQueryFactory {
 	 * @param evaluationContextProvider
 	 * @return the {@link RepositoryQuery} derived from the annotation or {@code null} if no annotation found.
 	 */
+	@Nullable
 	AbstractJpaQuery fromQueryAnnotation(JpaQueryMethod method, EntityManager em,
 			EvaluationContextProvider evaluationContextProvider) {
 
@@ -62,7 +65,8 @@ enum JpaQueryFactory {
 	 * @param evaluationContextProvider
 	 * @return
 	 */
-	AbstractJpaQuery fromMethodWithQueryString(JpaQueryMethod method, EntityManager em, String queryString,
+	@Nullable
+	AbstractJpaQuery fromMethodWithQueryString(JpaQueryMethod method, EntityManager em, @Nullable String queryString,
 			EvaluationContextProvider evaluationContextProvider) {
 
 		if (queryString == null) {
@@ -80,6 +84,7 @@ enum JpaQueryFactory {
 	 * @param em must not be {@literal null}.
 	 * @return
 	 */
+	@Nullable
 	public StoredProcedureJpaQuery fromProcedureAnnotation(JpaQueryMethod method, EntityManager em) {
 
 		if (!method.isProcedureQuery()) {
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryLookupStrategy.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryLookupStrategy.java
index cbafb058d..9cee79e81 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryLookupStrategy.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryLookupStrategy.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2016 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,13 +28,15 @@ import org.springframework.data.repository.query.EvaluationContextProvider;
 import org.springframework.data.repository.query.QueryLookupStrategy;
 import org.springframework.data.repository.query.QueryLookupStrategy.Key;
 import org.springframework.data.repository.query.RepositoryQuery;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
  * Query lookup strategy to execute finders.
- * 
+ *
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public final class JpaQueryLookupStrategy {
 
@@ -45,7 +47,7 @@ public final class JpaQueryLookupStrategy {
 
 	/**
 	 * Base class for {@link QueryLookupStrategy} implementations that need access to an {@link EntityManager}.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
@@ -56,7 +58,7 @@ public final class JpaQueryLookupStrategy {
 
 		/**
 		 * Creates a new {@link AbstractQueryLookupStrategy}.
-		 * 
+		 *
 		 * @param em
 		 * @param extractor
 		 * @param evaluationContextProvider
@@ -67,7 +69,7 @@ public final class JpaQueryLookupStrategy {
 			this.provider = extractor;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.repository.query.QueryLookupStrategy#resolveQuery(java.lang.reflect.Method, org.springframework.data.repository.core.RepositoryMetadata, org.springframework.data.projection.ProjectionFactory, org.springframework.data.repository.core.NamedQueries)
 		 */
@@ -82,7 +84,7 @@ public final class JpaQueryLookupStrategy {
 
 	/**
 	 * {@link QueryLookupStrategy} to create a query from the method name.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
@@ -112,7 +114,7 @@ public final class JpaQueryLookupStrategy {
 	/**
 	 * {@link QueryLookupStrategy} that tries to detect a declared query declared via {@link Query} annotation followed by
 	 * a JPA named query lookup.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
@@ -122,7 +124,7 @@ public final class JpaQueryLookupStrategy {
 
 		/**
 		 * Creates a new {@link DeclaredQueryLookupStrategy}.
-		 * 
+		 *
 		 * @param em
 		 * @param extractor
 		 * @param evaluationContextProvider
@@ -174,7 +176,7 @@ public final class JpaQueryLookupStrategy {
 	 * {@link QueryLookupStrategy} to try to detect a declared query first (
 	 * {@link org.springframework.data.jpa.repository.Query}, JPA named query). In case none is found we fall back on
 	 * query creation.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
@@ -185,7 +187,7 @@ public final class JpaQueryLookupStrategy {
 
 		/**
 		 * Creates a new {@link CreateIfNotFoundQueryLookupStrategy}.
-		 * 
+		 *
 		 * @param em
 		 * @param extractor
 		 * @param createStrategy
@@ -218,14 +220,14 @@ public final class JpaQueryLookupStrategy {
 
 	/**
 	 * Creates a {@link QueryLookupStrategy} for the given {@link EntityManager} and {@link Key}.
-	 * 
+	 *
 	 * @param em must not be {@literal null}.
 	 * @param key may be {@literal null}.
 	 * @param extractor must not be {@literal null}.
 	 * @param evaluationContextProvider must not be {@literal null}.
 	 * @return
 	 */
-	public static QueryLookupStrategy create(EntityManager em, Key key, QueryExtractor extractor,
+	public static QueryLookupStrategy create(EntityManager em, @Nullable Key key, QueryExtractor extractor,
 			EvaluationContextProvider evaluationContextProvider) {
 
 		Assert.notNull(em, "EntityManager must not be null!");
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
index 264c27aa0..d6bc7ddda 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
@@ -41,6 +41,7 @@ import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.query.Parameter;
 import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.QueryMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -64,7 +65,7 @@ public class JpaQueryMethod extends QueryMethod {
 
 	static {
 
-		Set<Class<?>> types = new HashSet<Class<?>>();
+		Set<Class<?>> types = new HashSet<>();
 		types.add(byte[].class);
 		types.add(Byte[].class);
 		types.add(char[].class);
@@ -76,14 +77,15 @@ public class JpaQueryMethod extends QueryMethod {
 	private final QueryExtractor extractor;
 	private final Method method;
 
-	private StoredProcedureAttributes storedProcedureAttributes;
+	private @Nullable StoredProcedureAttributes storedProcedureAttributes;
 
 	/**
 	 * Creates a {@link JpaQueryMethod}.
 	 *
 	 * @param method must not be {@literal null}
-	 * @param extractor must not be {@literal null}
 	 * @param metadata must not be {@literal null}
+	 * @param factory must not be {@literal null}
+	 * @param extractor must not be {@literal null}
 	 */
 	public JpaQueryMethod(Method method, RepositoryMetadata metadata, ProjectionFactory factory,
 			QueryExtractor extractor) {
@@ -115,8 +117,9 @@ public class JpaQueryMethod extends QueryMethod {
 				continue;
 			}
 
-			if (!annotatedQuery.contains(String.format(":%s", parameter.getName().get()))
-					&& !annotatedQuery.contains(String.format("#%s", parameter.getName().get()))) {
+			if (StringUtils.isEmpty(annotatedQuery)
+					|| !annotatedQuery.contains(String.format(":%s", parameter.getName().get()))
+							&& !annotatedQuery.contains(String.format("#%s", parameter.getName().get()))) {
 				throw new IllegalStateException(
 						String.format("Using named parameters for method %s but parameter '%s' not found in annotated query '%s'!",
 								method, parameter.getName(), annotatedQuery));
@@ -152,7 +155,7 @@ public class JpaQueryMethod extends QueryMethod {
 	 */
 	List<QueryHint> getHints() {
 
-		List<QueryHint> result = new ArrayList<QueryHint>();
+		List<QueryHint> result = new ArrayList<>();
 
 		QueryHints hints = AnnotatedElementUtils.findMergedAnnotation(method, QueryHints.class);
 		if (hints != null) {
@@ -167,6 +170,7 @@ public class JpaQueryMethod extends QueryMethod {
 	 *
 	 * @return
 	 */
+	@Nullable
 	LockModeType getLockModeType() {
 
 		return (LockModeType) Optional.ofNullable(AnnotatedElementUtils.findMergedAnnotation(method, Lock.class)) //
@@ -180,6 +184,7 @@ public class JpaQueryMethod extends QueryMethod {
 	 * @return
 	 * @since 1.6
 	 */
+	@Nullable
 	JpaEntityGraph getEntityGraph() {
 
 		EntityGraph annotation = AnnotatedElementUtils.findMergedAnnotation(method, EntityGraph.class);
@@ -224,18 +229,39 @@ public class JpaQueryMethod extends QueryMethod {
 	 *
 	 * @return
 	 */
+	@Nullable
 	String getAnnotatedQuery() {
 
 		String query = getAnnotationValue("value", String.class);
 		return StringUtils.hasText(query) ? query : null;
 	}
 
+	/**
+	 * Returns the required query string declared in a {@link Query} annotation or throws {@link IllegalStateException} if
+	 * neither the annotation found nor the attribute was specified.
+	 *
+	 * @return
+	 * @throws IllegalStateException if no {@link Query} annotation is present or the query is empty.
+	 * @since 2.0
+	 */
+	String getRequiredAnnotatedQuery() throws IllegalStateException {
+
+		String query = getAnnotatedQuery();
+
+		if (query != null) {
+			return query;
+		}
+
+		throw new IllegalStateException(String.format("No annotated query found for query method %s!", getName()));
+	}
+
 	/**
 	 * Returns the countQuery string declared in a {@link Query} annotation or {@literal null} if neither the annotation
 	 * found nor the attribute was specified.
 	 *
 	 * @return
 	 */
+	@Nullable
 	String getCountQuery() {
 
 		String countQuery = getAnnotationValue("countQuery", String.class);
@@ -249,6 +275,7 @@ public class JpaQueryMethod extends QueryMethod {
 	 * @return
 	 * @since 1.6
 	 */
+	@Nullable
 	String getCountQueryProjection() {
 
 		String countProjection = getAnnotationValue("countProjection", String.class);
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaResultConverters.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaResultConverters.java
index ac6b0653d..28306002d 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaResultConverters.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaResultConverters.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,12 +24,14 @@ import java.sql.SQLException;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.dao.CleanupFailureDataAccessException;
 import org.springframework.dao.DataRetrievalFailureException;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 
 /**
  * Container for additional JPA result {@link Converter}s.
  * 
  * @author Thomas Darimont
+ * @author Mark Paluch
  * @since 1.6
  */
 final class JpaResultConverters {
@@ -48,8 +50,9 @@ final class JpaResultConverters {
 
 		INSTANCE;
 
+		@Nullable
 		@Override
-		public byte[] convert(Blob source) {
+		public byte[] convert(@Nullable Blob source) {
 
 			if (source == null) {
 				return null;
@@ -67,9 +70,7 @@ final class JpaResultConverters {
 					return baos.toByteArray();
 				}
 
-			} catch (SQLException e) {
-				throw new DataRetrievalFailureException("Couldn't retrieve data from blob.", e);
-			} catch (IOException e) {
+			} catch (SQLException | IOException e) {
 				throw new DataRetrievalFailureException("Couldn't retrieve data from blob.", e);
 			} finally {
 				if (blobStream != null) {
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java
index 860c6aed7..e86ba84ea 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/NamedQuery.java
@@ -25,12 +25,14 @@ import org.springframework.data.jpa.provider.QueryExtractor;
 import org.springframework.data.repository.query.Parameters;
 import org.springframework.data.repository.query.QueryCreationException;
 import org.springframework.data.repository.query.RepositoryQuery;
+import org.springframework.lang.Nullable;
 
 /**
  * Implementation of {@link RepositoryQuery} based on {@link javax.persistence.NamedQuery}s.
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 final class NamedQuery extends AbstractJpaQuery {
 
@@ -43,7 +45,7 @@ final class NamedQuery extends AbstractJpaQuery {
 
 	private final String queryName;
 	private final String countQueryName;
-	private final String countProjection;
+	private final @Nullable String countProjection;
 	private final QueryExtractor extractor;
 	private final boolean namedCountQueryIsPresent;
 
@@ -112,6 +114,7 @@ final class NamedQuery extends AbstractJpaQuery {
 	 * @param method
 	 * @return
 	 */
+	@Nullable
 	public static RepositoryQuery lookupFrom(JpaQueryMethod method, EntityManager em) {
 
 		final String queryName = method.getNamedQueryName();
@@ -157,6 +160,11 @@ final class NamedQuery extends AbstractJpaQuery {
 		} else {
 			Query query = createQuery(values);
 			String queryString = extractor.extractQueryString(query);
+
+			if (queryString == null) {
+				throw new IllegalStateException(String.format("Cannot extract query string for query %s is null!", query));
+			}
+
 			countQuery = em.createQuery(QueryUtils.createCountQueryFor(queryString, countProjection), Long.class);
 		}
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinder.java b/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinder.java
index 31ea8a77a..1225c89ab 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinder.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinder.java
@@ -63,7 +63,7 @@ public class ParameterBinder {
 	 * Binds the parameters to the given query and applies special parameter types (e.g. pagination).
 	 *
 	 * @param query must not be {@literal null}.
-	 * @param values values of method parameters to be assigned to the query parame
+	 * @param values values of method parameters to be assigned to the query parameters.
 	 */
 	Query bindAndPrepare(Query query, Object[] values) {
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinderFactory.java b/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinderFactory.java
index 1ed01b4e0..a83724159 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinderFactory.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/ParameterBinderFactory.java
@@ -18,6 +18,7 @@ package org.springframework.data.jpa.repository.query;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import org.springframework.data.jpa.repository.query.JpaParameters.JpaParameter;
 import org.springframework.data.jpa.repository.query.ParameterMetadataProvider.ParameterMetadata;
@@ -25,6 +26,7 @@ import org.springframework.data.jpa.repository.query.StringQuery.ParameterBindin
 import org.springframework.data.repository.query.EvaluationContextProvider;
 import org.springframework.data.util.StreamUtils;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -123,7 +125,7 @@ class ParameterBinderFactory {
 		return createSetters(null, parameterBindings, factories);
 	}
 
-	private static Iterable<QueryParameterSetter> createSetters(String queryString,
+	private static Iterable<QueryParameterSetter> createSetters(@Nullable String queryString,
 			List<ParameterBinding> parameterBindings, QueryParameterSetterFactory... strategies) {
 
 		return parameterBindings.stream() //
@@ -132,11 +134,11 @@ class ParameterBinderFactory {
 	}
 
 	private static QueryParameterSetter createQueryParameterSetter(ParameterBinding binding,
-			QueryParameterSetterFactory[] strategies, String queryString) {
+			QueryParameterSetterFactory[] strategies, @Nullable String queryString) {
 
 		return Arrays.stream(strategies)//
 				.map(it -> it.create(binding, queryString))//
-				.filter(it -> it != null)//
+				.filter(Objects::nonNull)//
 				.findFirst()//
 				.orElse(QueryParameterSetter.NOOP);
 	}
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/ParameterMetadataProvider.java b/src/main/java/org/springframework/data/jpa/repository/query/ParameterMetadataProvider.java
index 5ee7c1a6a..d1149839f 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/ParameterMetadataProvider.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/ParameterMetadataProvider.java
@@ -32,6 +32,7 @@ import org.springframework.data.repository.query.ParametersParameterAccessor;
 import org.springframework.data.repository.query.parser.Part;
 import org.springframework.data.repository.query.parser.Part.Type;
 import org.springframework.expression.Expression;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
@@ -49,7 +50,7 @@ class ParameterMetadataProvider {
 	private final CriteriaBuilder builder;
 	private final Iterator<? extends Parameter> parameters;
 	private final List<ParameterMetadata<?>> expressions;
-	private final Iterator<Object> bindableParameterValues;
+	private final @Nullable Iterator<Object> bindableParameterValues;
 	private final PersistenceProvider persistenceProvider;
 
 	/**
@@ -88,7 +89,7 @@ class ParameterMetadataProvider {
 	 * @param parameters must not be {@literal null}.
 	 * @param provider must not be {@literal null}.
 	 */
-	private ParameterMetadataProvider(CriteriaBuilder builder, Iterator<Object> bindableParameterValues,
+	private ParameterMetadataProvider(CriteriaBuilder builder, @Nullable Iterator<Object> bindableParameterValues,
 			Parameters<?, ?> parameters, PersistenceProvider provider) {
 
 		Assert.notNull(builder, "CriteriaBuilder must not be null!");
@@ -190,7 +191,8 @@ class ParameterMetadataProvider {
 		 * @param value
 		 * @param provider
 		 */
-		public ParameterMetadata(ParameterExpression<T> expression, Type type, Object value, PersistenceProvider provider) {
+		public ParameterMetadata(ParameterExpression<T> expression, Type type, @Nullable Object value,
+				PersistenceProvider provider) {
 
 			this.expression = expression;
 			this.persistenceProvider = provider;
@@ -221,6 +223,7 @@ class ParameterMetadataProvider {
 		 * @param value must not be {@literal null}.
 		 * @return
 		 */
+		@Nullable
 		public Object prepare(Object value) {
 
 			Assert.notNull(value, "Value must not be null!");
@@ -254,7 +257,8 @@ class ParameterMetadataProvider {
 		 * @param value
 		 * @return
 		 */
-		private static Collection<?> toCollection(Object value) {
+		@Nullable
+		private static Collection<?> toCollection(@Nullable Object value) {
 
 			if (value == null) {
 				return null;
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/PartTreeJpaQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/PartTreeJpaQuery.java
index 3ddb0b9fc..963a1b12d 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/PartTreeJpaQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/PartTreeJpaQuery.java
@@ -33,6 +33,7 @@ import org.springframework.data.repository.query.ParametersParameterAccessor;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.data.repository.query.parser.PartTree;
+import org.springframework.lang.Nullable;
 
 /**
  * A {@link AbstractJpaQuery} implementation based on a {@link PartTree}.
@@ -41,6 +42,7 @@ import org.springframework.data.repository.query.parser.PartTree;
  * @author Thomas Darimont
  * @author Christoph Strobl
  * @author Jens Schauder
+ * @author Mark Paluch
  */
 public class PartTreeJpaQuery extends AbstractJpaQuery {
 
@@ -116,9 +118,9 @@ public class PartTreeJpaQuery extends AbstractJpaQuery {
 	 */
 	private class QueryPreparer {
 
-		private final CriteriaQuery<?> cachedCriteriaQuery;
-		private final ParameterBinder cachedParameterBinder;
-		private final List<ParameterMetadata<?>> expressions;
+		private final @Nullable CriteriaQuery<?> cachedCriteriaQuery;
+		private final @Nullable ParameterBinder cachedParameterBinder;
+		private final @Nullable List<ParameterMetadata<?>> expressions;
 		private final PersistenceProvider persistenceProvider;
 
 		QueryPreparer(PersistenceProvider persistenceProvider, boolean recreateQueries) {
@@ -156,6 +158,10 @@ public class PartTreeJpaQuery extends AbstractJpaQuery {
 
 			TypedQuery<?> jpaQuery = createQuery(criteriaQuery);
 
+			if (parameterBinder == null) {
+				throw new IllegalStateException("ParameterBinder is null!");
+			}
+
 			return restrictMaxResultsIfNecessary(invokeBinding(parameterBinder, jpaQuery, values));
 		}
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetter.java b/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetter.java
index cccb49d45..e1773ee32 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetter.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetter.java
@@ -23,6 +23,7 @@ import javax.persistence.Query;
 import javax.persistence.TemporalType;
 import javax.persistence.criteria.ParameterExpression;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -30,6 +31,7 @@ import org.springframework.util.Assert;
  * {@literal Query.setParameter}.
  *
  * @author Jens Schauder
+ * @author Mark Paluch
  * @since 2.0
  */
 interface QueryParameterSetter {
@@ -46,17 +48,17 @@ interface QueryParameterSetter {
 
 		private final Function<Object[], Object> valueExtractor;
 		private final Parameter<?> parameter;
-		private final TemporalType temporalType;
+		private final @Nullable TemporalType temporalType;
 		private final boolean lenient;
 
 		/**
 		 * @param valueExtractor must not be {@literal null}.
 		 * @param parameter must not be {@literal null}.
-		 * @param temporalType must not be {@literal null}.
+		 * @param temporalType may be {@literal null}.
 		 * @param lenient must not be {@literal null}.
 		 */
 		NamedOrIndexedQueryParameterSetter(Function<Object[], Object> valueExtractor, Parameter<?> parameter,
-				TemporalType temporalType, boolean lenient) {
+				@Nullable TemporalType temporalType, boolean lenient) {
 
 			Assert.notNull(valueExtractor, "ValueExtractor must not be null!");
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetterFactory.java b/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetterFactory.java
index c9ccd6f14..6b02a50ea 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetterFactory.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/QueryParameterSetterFactory.java
@@ -31,6 +31,7 @@ import org.springframework.data.repository.query.Parameters;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -39,15 +40,17 @@ import org.springframework.util.Assert;
  *
  * @author Jens Schauder
  * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 2.0
  */
 abstract class QueryParameterSetterFactory {
 
-	abstract QueryParameterSetter create(ParameterBinding binding, String queryString);
+	@Nullable
+	abstract QueryParameterSetter create(ParameterBinding binding, @Nullable String queryString);
 
 	/**
 	 * Creates a new {@link QueryParameterSetterFactory} for the given {@link JpaParameters}.
-	 * 
+	 *
 	 * @param parameters must not be {@literal null}.
 	 * @return a basic {@link QueryParameterSetterFactory} that can handle named and index parameters.
 	 */
@@ -61,7 +64,7 @@ abstract class QueryParameterSetterFactory {
 	/**
 	 * Creates a new {@link QueryParameterSetterFactory} using the given {@link JpaParameters} and
 	 * {@link ParameterMetadata}.
-	 * 
+	 *
 	 * @param parameters must not be {@literal null}.
 	 * @param metadata must not be {@literal null}.
 	 * @return a {@link QueryParameterSetterFactory} for criteria Queries.
@@ -77,7 +80,7 @@ abstract class QueryParameterSetterFactory {
 	/**
 	 * Creates a new {@link QueryParameterSetterFactory} for the given {@link SpelExpressionParser},
 	 * {@link EvaluationContextProvider} and {@link Parameters}.
-	 * 
+	 *
 	 * @param parser must not be {@literal null}.
 	 * @param evaluationContextProvider must not be {@literal null}.
 	 * @param parameters must not be {@literal null}.
@@ -104,10 +107,10 @@ abstract class QueryParameterSetterFactory {
 	 * @param lenient when true certain exceptions thrown when setting the query parameters get ignored.
 	 */
 	private static QueryParameterSetter createSetter(Function<Object[], Object> valueExtractor, ParameterBinding binding,
-			JpaParameter parameter, boolean lenient) {
+			@Nullable JpaParameter parameter, boolean lenient) {
 
 		TemporalType temporalType = parameter != null && parameter.isTemporalParameter() //
-				? parameter.getTemporalType() //
+				? parameter.getRequiredTemporalType() //
 				: null;
 
 		return new NamedOrIndexedQueryParameterSetter(valueExtractor.andThen(binding::prepare),
@@ -148,8 +151,9 @@ abstract class QueryParameterSetterFactory {
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.repository.query.QueryParameterSetterFactory#create(org.springframework.data.jpa.repository.query.StringQuery.ParameterBinding, java.lang.String)
 		 */
+		@Nullable
 		@Override
-		public QueryParameterSetter create(ParameterBinding binding, String queryString) {
+		public QueryParameterSetter create(ParameterBinding binding, @Nullable String queryString) {
 
 			if (!binding.isExpression()) {
 				return null;
@@ -162,11 +166,12 @@ abstract class QueryParameterSetterFactory {
 
 		/**
 		 * Evaluates the given {@link Expression} against the given values.
-		 * 
+		 *
 		 * @param expression must not be {@literal null}.
 		 * @param values must not be {@literal null}.
 		 * @return the result of the evaluation.
 		 */
+		@Nullable
 		private Object evaluateExpression(Expression expression, Object[] values) {
 
 			EvaluationContext context = evaluationContextProvider.getEvaluationContext(parameters, values);
@@ -200,23 +205,24 @@ abstract class QueryParameterSetterFactory {
 		 * @see org.springframework.data.jpa.repository.query.QueryParameterSetterFactory#create(org.springframework.data.jpa.repository.query.StringQuery.ParameterBinding, java.lang.String)
 		 */
 		@Override
-		public QueryParameterSetter create(ParameterBinding binding, String queryString) {
+		public QueryParameterSetter create(ParameterBinding binding, @Nullable String queryString) {
 
 			Assert.notNull(binding, "Binding must not be null.");
 
 			JpaParameter parameter = QueryUtils.hasNamedParameter(queryString) //
 					? findParameterForBinding(binding) //
-					: parameters.getBindableParameter(binding.getPosition() - 1);
+					: parameters.getBindableParameter(binding.getRequiredPosition() - 1);
 
 			return parameter == null //
 					? QueryParameterSetter.NOOP //
 					: createSetter(values -> getValue(values, parameter), binding, parameter, false);
 		}
 
+		@Nullable
 		private JpaParameter findParameterForBinding(ParameterBinding binding) {
 
 			return parameters.getBindableParameters().stream() //
-					.filter(candidate -> binding.getName().equals(getName(candidate))) //
+					.filter(candidate -> binding.getRequiredName().equals(getName(candidate))) //
 					.findFirst().orElse(null);
 		}
 
@@ -231,7 +237,7 @@ abstract class QueryParameterSetterFactory {
 
 	/**
 	 * {@link QueryParameterSetterFactory}
-	 * 
+	 *
 	 * @author Jens Schauder
 	 * @author Oliver Gierke
 	 */
@@ -243,7 +249,7 @@ abstract class QueryParameterSetterFactory {
 		/**
 		 * Creates a new {@link QueryParameterSetterFactory} from the given {@link JpaParameters} and
 		 * {@link ParameterMetadata}.
-		 * 
+		 *
 		 * @param parameters must not be {@literal null}.
 		 * @param metadata must not be {@literal null}.
 		 */
@@ -261,21 +267,22 @@ abstract class QueryParameterSetterFactory {
 		 * @see org.springframework.data.jpa.repository.query.QueryParameterSetterFactory#create(org.springframework.data.jpa.repository.query.StringQuery.ParameterBinding, java.lang.String)
 		 */
 		@Override
-		public QueryParameterSetter create(ParameterBinding binding, String queryString) {
+		public QueryParameterSetter create(ParameterBinding binding, @Nullable String queryString) {
 
-			ParameterMetadata<?> metadata = expressions.get(binding.getPosition() - 1);
+			ParameterMetadata<?> metadata = expressions.get(binding.getRequiredPosition() - 1);
 
 			if (metadata.isIsNullParameter()) {
 				return QueryParameterSetter.NOOP;
 			}
 
-			JpaParameter parameter = parameters.getBindableParameter(binding.getPosition() - 1);
-			TemporalType temporalType = parameter.isTemporalParameter() ? parameter.getTemporalType() : null;
+			JpaParameter parameter = parameters.getBindableParameter(binding.getRequiredPosition() - 1);
+			TemporalType temporalType = parameter.isTemporalParameter() ? parameter.getRequiredTemporalType() : null;
 
 			return new NamedOrIndexedQueryParameterSetter(values -> getAndPrepare(parameter, metadata, values),
 					metadata.getExpression(), temporalType, false);
 		}
 
+		@Nullable
 		private Object getAndPrepare(JpaParameter parameter, ParameterMetadata<?> metadata, Object[] values) {
 
 			JpaParametersParameterAccessor accessor = new JpaParametersParameterAccessor(parameters, values);
@@ -287,17 +294,17 @@ abstract class QueryParameterSetterFactory {
 	private static class ParameterImpl<T> implements javax.persistence.Parameter<T> {
 
 		private final Class<T> parameterType;
-		private final String name;
-		private final Integer position;
+		private final @Nullable String name;
+		private final @Nullable Integer position;
 
 		/**
 		 * Creates a new {@link ParameterImpl} for the given {@link JpaParameter} and {@link ParameterBinding}.
-		 * 
+		 *
 		 * @param parameter can be {@literal null}.
 		 * @param binding must not be {@literal null}.
 		 * @return a {@link javax.persistence.Parameter} object based on the information from the arguments.
 		 */
-		static javax.persistence.Parameter<?> of(JpaParameter parameter, ParameterBinding binding) {
+		static javax.persistence.Parameter<?> of(@Nullable JpaParameter parameter, ParameterBinding binding) {
 
 			Class<?> type = parameter == null ? Object.class : parameter.getType();
 
@@ -306,37 +313,39 @@ abstract class QueryParameterSetterFactory {
 
 		/**
 		 * Creates a new {@link ParameterImpl} for the given name, position and parameter type.
-		 * 
+		 *
 		 * @param parameterType must not be {@literal null}.
 		 * @param name can be {@literal null}.
 		 * @param position can be {@literal null}.
 		 */
-		private ParameterImpl(Class<T> parameterType, String name, Integer position) {
+		private ParameterImpl(Class<T> parameterType, @Nullable String name, @Nullable Integer position) {
 
 			this.name = name;
 			this.position = position;
 			this.parameterType = parameterType;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see javax.persistence.Parameter#getName()
 		 */
+		@Nullable
 		@Override
 		public String getName() {
 			return name;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see javax.persistence.Parameter#getPosition()
 		 */
+		@Nullable
 		@Override
 		public Integer getPosition() {
 			return position;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see javax.persistence.Parameter#getParameterType()
 		 */
@@ -345,7 +354,8 @@ abstract class QueryParameterSetterFactory {
 			return parameterType;
 		}
 
-		private static String getName(JpaParameter parameter, ParameterBinding binding) {
+		@Nullable
+		private static String getName(@Nullable JpaParameter parameter, ParameterBinding binding) {
 
 			if (parameter == null) {
 				return binding.getName();
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/QueryUtils.java b/src/main/java/org/springframework/data/jpa/repository/query/QueryUtils.java
index f7541c553..aa6dd1bbb 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/QueryUtils.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/QueryUtils.java
@@ -57,6 +57,7 @@ import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Order;
 import org.springframework.data.jpa.domain.JpaSort.JpaOrder;
 import org.springframework.data.mapping.PropertyPath;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -224,14 +225,14 @@ public abstract class QueryUtils {
 	 * 
 	 * @param query the query string to which sorting is applied. Must not be {@literal null} or empty.
 	 * @param sort the sort specification to apply.
-	 * @param alias the alias to be used in the order by clause. Must not be {@literal null} or empty.
+	 * @param alias the alias to be used in the order by clause. May be {@literal null} or empty.
 	 * @return the modified query string.
 	 */
-	public static String applySorting(String query, Sort sort, String alias) {
+	public static String applySorting(String query, Sort sort, @Nullable String alias) {
 
 		Assert.hasText(query, "Query must not be null or empty!");
 
-		if (null == sort || !sort.iterator().hasNext()) {
+		if (sort.isUnsorted()) {
 			return query;
 		}
 
@@ -264,7 +265,8 @@ public abstract class QueryUtils {
 	 * @param order the order object to build the clause for.
 	 * @return
 	 */
-	private static String getOrderClause(Set<String> joinAliases, Set<String> functionAlias, String alias, Order order) {
+	private static String getOrderClause(Set<String> joinAliases, Set<String> functionAlias, @Nullable String alias,
+			Order order) {
 
 		String property = order.getProperty();
 
@@ -345,6 +347,7 @@ public abstract class QueryUtils {
 	 * @param query
 	 * @return
 	 */
+	@Nullable
 	public static String detectAlias(String query) {
 
 		Matcher matcher = ALIAS_MATCH.matcher(query);
@@ -421,7 +424,7 @@ public abstract class QueryUtils {
 	 * @return
 	 * @since 1.6
 	 */
-	public static String createCountQueryFor(String originalQuery, String countProjection) {
+	public static String createCountQueryFor(String originalQuery, @Nullable String countProjection) {
 
 		Assert.hasText(originalQuery, "OriginalQuery must not be null or empty!");
 
@@ -472,7 +475,7 @@ public abstract class QueryUtils {
 	 * @param query can be {@literal null} or empty.
 	 * @return
 	 */
-	public static boolean hasNamedParameter(String query) {
+	public static boolean hasNamedParameter(@Nullable String query) {
 		return StringUtils.hasText(query) && NAMED_PARAMETER.matcher(query).find();
 	}
 
@@ -488,7 +491,7 @@ public abstract class QueryUtils {
 
 		List<javax.persistence.criteria.Order> orders = new ArrayList<javax.persistence.criteria.Order>();
 
-		if (sort == null) {
+		if (sort.isUnsorted()) {
 			return orders;
 		}
 
@@ -556,7 +559,7 @@ public abstract class QueryUtils {
 	@SuppressWarnings("unchecked")
 	static <T> Expression<T> toExpressionRecursively(From<?, ?> from, PropertyPath property) {
 
-		Bindable<?> propertyPathModel = null;
+		Bindable<?> propertyPathModel;
 		Bindable<?> model = from.getModel();
 		String segment = property.getSegment();
 
@@ -584,11 +587,11 @@ public abstract class QueryUtils {
 	 * Returns whether the given {@code propertyPathModel} requires the creation of a join. This is the case if we find a
 	 * non-optional association.
 	 * 
-	 * @param propertyPathModel must not be {@literal null}.
+	 * @param propertyPathModel may be {@literal null}.
 	 * @param forPluralAttribute
 	 * @return
 	 */
-	private static boolean requiresJoin(Bindable<?> propertyPathModel, boolean forPluralAttribute) {
+	private static boolean requiresJoin(@Nullable Bindable<?> propertyPathModel, boolean forPluralAttribute) {
 
 		if (propertyPathModel == null && forPluralAttribute) {
 			return true;
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/SimpleJpaQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/SimpleJpaQuery.java
index 2ee943f9a..22325e278 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/SimpleJpaQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/SimpleJpaQuery.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2013 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@ import org.springframework.expression.spel.standard.SpelExpressionParser;
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 final class SimpleJpaQuery extends AbstractStringBasedJpaQuery {
 
@@ -42,7 +43,7 @@ final class SimpleJpaQuery extends AbstractStringBasedJpaQuery {
 	 */
 	public SimpleJpaQuery(JpaQueryMethod method, EntityManager em, EvaluationContextProvider evaluationContextProvider,
 			SpelExpressionParser parser) {
-		this(method, em, method.getAnnotatedQuery(), evaluationContextProvider, parser);
+		this(method, em, method.getRequiredAnnotatedQuery(), evaluationContextProvider, parser);
 	}
 
 	/**
@@ -73,7 +74,7 @@ final class SimpleJpaQuery extends AbstractStringBasedJpaQuery {
 	 * @param query
 	 * @param em
 	 */
-	private final void validateQuery(String query, String errorMessage) {
+	private void validateQuery(String query, String errorMessage) {
 
 		if (getQueryMethod().isProcedureQuery()) {
 			return;
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributeSource.java b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributeSource.java
index 751c71f1c..4976b3ac3 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributeSource.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributeSource.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import javax.persistence.NamedStoredProcedureQuery;
 import javax.persistence.StoredProcedureParameter;
 
 import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -34,6 +35,7 @@ import org.springframework.util.StringUtils;
  * @author Thomas Darimont
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.6
  */
 enum StoredProcedureAttributeSource {
@@ -157,6 +159,7 @@ enum StoredProcedureAttributeSource {
 	 * @param procedure must not be {@literal null}.
 	 * @return
 	 */
+	@Nullable
 	private NamedStoredProcedureQuery tryFindAnnotatedNamedStoredProcedureQuery(Method method,
 			JpaEntityMetadata<?> entityMetadata, Procedure procedure) {
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributes.java b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributes.java
index 2c6c0f931..2e5453057 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributes.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureAttributes.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@ package org.springframework.data.jpa.repository.query;
 
 import javax.persistence.StoredProcedureQuery;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -25,6 +26,7 @@ import org.springframework.util.StringUtils;
  * 
  * @author Thomas Darimont
  * @author Oliver Gierke
+ * @author Mark Paluch
  * @since 1.6
  */
 class StoredProcedureAttributes {
@@ -45,8 +47,8 @@ class StoredProcedureAttributes {
 	 * @param outputParameterIndex must not be {@literal null}
 	 * @param outputParameterType
 	 */
-	public StoredProcedureAttributes(String procedureName, String outputParameterName, Class<?> outputParameterType,
-			boolean namedStoredProcedure) {
+	public StoredProcedureAttributes(String procedureName, @Nullable String outputParameterName,
+			Class<?> outputParameterType, boolean namedStoredProcedure) {
 
 		Assert.notNull(procedureName, "ProcedureName must not be null!");
 		Assert.notNull(outputParameterType, "OutputParameterType must not be null!");
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureJpaQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureJpaQuery.java
index 03f704c1f..7e48b1cfe 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureJpaQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/StoredProcedureJpaQuery.java
@@ -24,6 +24,7 @@ import javax.persistence.TypedQuery;
 import org.springframework.data.jpa.repository.query.JpaParameters.JpaParameter;
 import org.springframework.data.repository.query.Parameter;
 import org.springframework.data.repository.query.QueryMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -35,6 +36,7 @@ import org.springframework.util.StringUtils;
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Jens Schauder
+ * @author Mark Paluch
  * @since 1.6
  */
 class StoredProcedureJpaQuery extends AbstractJpaQuery {
@@ -96,7 +98,7 @@ class StoredProcedureJpaQuery extends AbstractJpaQuery {
 	 */
 	@Override
 	protected TypedQuery<Long> doCreateCountQuery(Object[] values) {
-		return null;
+		throw new UnsupportedOperationException("StoredProcedureQuery does not support count queries!");
 	}
 
 	/**
@@ -104,6 +106,7 @@ class StoredProcedureJpaQuery extends AbstractJpaQuery {
 	 * 
 	 * @param storedProcedureQuery must not be {@literal null}.
 	 */
+	@Nullable
 	Object extractOutputValue(StoredProcedureQuery storedProcedureQuery) {
 
 		Assert.notNull(storedProcedureQuery, "StoredProcedureQuery must not be null!");
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/StringQuery.java b/src/main/java/org/springframework/data/jpa/repository/query/StringQuery.java
index d76c0ec77..26af01449 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/StringQuery.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/StringQuery.java
@@ -27,6 +27,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.springframework.data.repository.query.parser.Part.Type;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -47,7 +48,7 @@ class StringQuery {
 
 	private final String query;
 	private final List<ParameterBinding> bindings;
-	private final String alias;
+	private final @Nullable String alias;
 	private final boolean hasConstructorExpression;
 
 	/**
@@ -83,7 +84,7 @@ class StringQuery {
 	/**
 	 * Returns the query string.
 	 */
-	public String getQueryString() {
+	String getQueryString() {
 		return query;
 	}
 
@@ -92,6 +93,7 @@ class StringQuery {
 	 * 
 	 * @return the alias
 	 */
+	@Nullable
 	String getAlias() {
 		return alias;
 	}
@@ -287,9 +289,9 @@ class StringQuery {
 			// character, while = does not.
 			LIKE("like "), IN("in "), AS_IS(null);
 
-			private final String keyword;
+			private final @Nullable String keyword;
 
-			ParameterBindingType(String keyword) {
+			ParameterBindingType(@Nullable String keyword) {
 				this.keyword = keyword;
 			}
 
@@ -299,6 +301,7 @@ class StringQuery {
 			 * 
 			 * @return the keyword
 			 */
+			@Nullable
 			public String getKeyword() {
 				return keyword;
 			}
@@ -331,9 +334,9 @@ class StringQuery {
 	 */
 	static class ParameterBinding {
 
-		private final String name;
-		private final String expression;
-		private final Integer position;
+		private final @Nullable String name;
+		private final @Nullable String expression;
+		private final @Nullable Integer position;
 
 		/**
 		 * Creates a new {@link ParameterBinding} for the parameter with the given position.
@@ -352,7 +355,7 @@ class StringQuery {
 		 * @param position of the parameter may be {@literal null}.
 		 * @param expression the expression to apply to any value for this parameter.
 		 */
-		ParameterBinding(String name, Integer position, String expression) {
+		ParameterBinding(@Nullable String name, @Nullable Integer position, @Nullable String expression) {
 
 			if (name == null) {
 				Assert.notNull(position, "Position must not be null!");
@@ -371,7 +374,7 @@ class StringQuery {
 		 * Returns whether the binding has the given name. Will always be {@literal false} in case the
 		 * {@link ParameterBinding} has been set up from a position.
 		 */
-		boolean hasName(String name) {
+		boolean hasName(@Nullable String name) {
 			return this.position == null && this.name != null && this.name.equals(name);
 		}
 
@@ -379,24 +382,58 @@ class StringQuery {
 		 * Returns whether the binding has the given position. Will always be {@literal false} in case the
 		 * {@link ParameterBinding} has been set up from a name.
 		 */
-		boolean hasPosition(Integer position) {
+		boolean hasPosition(@Nullable Integer position) {
 			return position != null && this.name == null && position.equals(this.position);
 		}
 
 		/**
 		 * @return the name
 		 */
+		@Nullable
 		public String getName() {
 			return name;
 		}
 
+		/**
+		 * @return the name
+		 * @throws IllegalStateException if the name is not available.
+		 * @since 2.0
+		 */
+		String getRequiredName() throws IllegalStateException {
+
+			String name = getName();
+
+			if (name != null) {
+				return name;
+			}
+
+			throw new IllegalStateException(String.format("Required name for %s not available!", this));
+		}
+
 		/**
 		 * @return the position
 		 */
+		@Nullable
 		Integer getPosition() {
 			return position;
 		}
 
+		/**
+		 * @return the position
+		 * @throws IllegalStateException if the position is not available.
+		 * @since 2.0
+		 */
+		int getRequiredPosition() throws IllegalStateException {
+
+			Integer position = getPosition();
+
+			if (position != null) {
+				return position;
+			}
+
+			throw new IllegalStateException(String.format("Required position for %s not available!", this));
+		}
+
 		/**
 		 * @return {@literal true} if this parameter binding is a synthetic SpEL expression.
 		 */
@@ -450,10 +487,12 @@ class StringQuery {
 		/**
 		 * @param valueToBind value to prepare
 		 */
-		public Object prepare(Object valueToBind) {
+		@Nullable
+		public Object prepare(@Nullable Object valueToBind) {
 			return valueToBind;
 		}
 
+		@Nullable
 		public String getExpression() {
 			return expression;
 		}
@@ -470,14 +509,14 @@ class StringQuery {
 		/**
 		 * Creates a new {@link InParameterBinding} for the parameter with the given name.
 		 */
-		InParameterBinding(String name, String expression) {
+		InParameterBinding(String name, @Nullable String expression) {
 			super(name, null, expression);
 		}
 
 		/**
 		 * Creates a new {@link InParameterBinding} for the parameter with the given position.
 		 */
-		InParameterBinding(int position, String expression) {
+		InParameterBinding(int position, @Nullable String expression) {
 			super(null, position, expression);
 		}
 
@@ -486,7 +525,7 @@ class StringQuery {
 		 * @see org.springframework.data.jpa.repository.query.StringQuery.ParameterBinding#prepare(java.lang.Object)
 		 */
 		@Override
-		public Object prepare(Object value) {
+		public Object prepare(@Nullable Object value) {
 
 			if (!ObjectUtils.isArray(value)) {
 				return value;
@@ -535,7 +574,7 @@ class StringQuery {
 		 * @param type must not be {@literal null}.
 		 * @param expression may be {@literal null}.
 		 */
-		LikeParameterBinding(String name, Type type, String expression) {
+		LikeParameterBinding(String name, Type type, @Nullable String expression) {
 
 			super(name, null, expression);
 
@@ -565,7 +604,7 @@ class StringQuery {
 		 * @param type must not be {@literal null}.
 		 * @param expression may be {@literal null}.
 		 */
-		LikeParameterBinding(int position, Type type, String expression) {
+		LikeParameterBinding(int position, Type type, @Nullable String expression) {
 
 			super(null, position, expression);
 
@@ -592,8 +631,9 @@ class StringQuery {
 		 * 
 		 * @param keyword
 		 */
+		@Nullable
 		@Override
-		public Object prepare(Object value) {
+		public Object prepare(@Nullable Object value) {
 
 			if (value == null) {
 				return null;
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/package-info.java b/src/main/java/org/springframework/data/jpa/repository/query/package-info.java
index 5d82778a6..9e269c303 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/package-info.java
@@ -1,5 +1,7 @@
 /**
  * Query implementation to exectue queries against JPA.
  */
+@NonNullApi
 package org.springframework.data.jpa.repository.query;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadata.java b/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadata.java
index a53966e53..65b589606 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadata.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadata.java
@@ -22,6 +22,7 @@ import java.util.Optional;
 import javax.persistence.LockModeType;
 
 import org.springframework.data.jpa.repository.EntityGraph;
+import org.springframework.lang.Nullable;
 
 /**
  * Interface to abstract {@link CrudMethodMetadata} that provide the {@link LockModeType} to be used for query
@@ -30,6 +31,7 @@ import org.springframework.data.jpa.repository.EntityGraph;
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public interface CrudMethodMetadata {
 
@@ -38,6 +40,7 @@ public interface CrudMethodMetadata {
 	 * 
 	 * @return
 	 */
+	@Nullable
 	LockModeType getLockModeType();
 
 	/**
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadataPostProcessor.java b/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadataPostProcessor.java
index c2c99f5f8..63eb3369a 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadataPostProcessor.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/CrudMethodMetadataPostProcessor.java
@@ -39,6 +39,7 @@ import org.springframework.data.jpa.repository.Lock;
 import org.springframework.data.jpa.repository.QueryHints;
 import org.springframework.data.repository.core.RepositoryInformation;
 import org.springframework.data.repository.core.support.RepositoryProxyPostProcessor;
+import org.springframework.lang.Nullable;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -51,10 +52,11 @@ import org.springframework.util.ClassUtils;
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, BeanClassLoaderAware {
 
-	private ClassLoader classLoader = ClassUtils.getDefaultClassLoader();
+	private @Nullable ClassLoader classLoader = ClassUtils.getDefaultClassLoader();
 
 	/* 
 	 * (non-Javadoc)
@@ -62,8 +64,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 	 */
 	@Override
 	public void setBeanClassLoader(ClassLoader classLoader) {
-		this.classLoader = classLoader == null ? ClassUtils.getDefaultClassLoader() : classLoader;
-
+		this.classLoader = classLoader;
 	}
 
 	/* 
@@ -97,7 +98,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
-	static enum CrudMethodMetadataPopulatingMethodInterceptor implements MethodInterceptor {
+	enum CrudMethodMetadataPopulatingMethodInterceptor implements MethodInterceptor {
 
 		INSTANCE;
 
@@ -146,7 +147,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 	 */
 	private static class DefaultCrudMethodMetadata implements CrudMethodMetadata {
 
-		private final LockModeType lockModeType;
+		private final @Nullable LockModeType lockModeType;
 		private final Map<String, Object> queryHints;
 		private final Optional<EntityGraph> entityGraph;
 		private final Method method;
@@ -156,7 +157,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 		 * 
 		 * @param method must not be {@literal null}.
 		 */
-		public DefaultCrudMethodMetadata(Method method) {
+		DefaultCrudMethodMetadata(Method method) {
 
 			Assert.notNull(method, "Method must not be null!");
 
@@ -170,6 +171,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 			return Optional.ofNullable(AnnotatedElementUtils.findMergedAnnotation(method, EntityGraph.class));
 		}
 
+		@Nullable
 		private static LockModeType findLockModeType(Method method) {
 
 			Lock annotation = AnnotatedElementUtils.findMergedAnnotation(method, Lock.class);
@@ -201,6 +203,7 @@ class CrudMethodMetadataPostProcessor implements RepositoryProxyPostProcessor, B
 		 * (non-Javadoc)
 		 * @see org.springframework.data.jpa.repository.support.CrudMethodMetadata#getLockModeType()
 		 */
+		@Nullable
 		@Override
 		public LockModeType getLockModeType() {
 			return lockModeType;
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/JpaEntityInformation.java b/src/main/java/org/springframework/data/jpa/repository/support/JpaEntityInformation.java
index c29fed745..d5cd623fd 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/JpaEntityInformation.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/JpaEntityInformation.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2014 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,12 +19,14 @@ import javax.persistence.metamodel.SingularAttribute;
 
 import org.springframework.data.jpa.repository.query.JpaEntityMetadata;
 import org.springframework.data.repository.core.EntityInformation;
+import org.springframework.lang.Nullable;
 
 /**
  * Extension of {@link EntityInformation} to capture additional JPA specific information about entities.
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public interface JpaEntityInformation<T, ID> extends EntityInformation<T, ID>, JpaEntityMetadata<T> {
 
@@ -33,8 +35,28 @@ public interface JpaEntityInformation<T, ID> extends EntityInformation<T, ID>, J
 	 * 
 	 * @return
 	 */
+	@Nullable
 	SingularAttribute<? super T, ?> getIdAttribute();
 
+	/**
+	 * Returns the required identifier type.
+	 *
+	 * @return the identifier type.
+	 * @throws IllegalArgumentException in case no id type could be obtained.
+	 * @since 2.0
+	 */
+	default SingularAttribute<? super T, ?> getRequiredIdAttribute() throws IllegalArgumentException {
+
+		SingularAttribute<? super T, ?> id = getIdAttribute();
+
+		if (id != null) {
+			return id;
+		}
+
+		throw new IllegalArgumentException(
+				String.format("Could not obtain required identifier attribute for type %s!", getEntityName()));
+	}
+
 	/**
 	 * Returns {@literal true} if the entity has a composite id.
 	 * 
@@ -57,5 +79,6 @@ public interface JpaEntityInformation<T, ID> extends EntityInformation<T, ID>, J
 	 * @param idAttribute
 	 * @return
 	 */
+	@Nullable
 	Object getCompositeIdAttributeValue(Object id, String idAttribute);
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java b/src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java
index 73a83c82c..45cc9bdbb 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java
@@ -19,9 +19,11 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 
 import javax.persistence.IdClass;
+import javax.persistence.metamodel.Attribute;
 import javax.persistence.metamodel.EntityType;
 import javax.persistence.metamodel.IdentifiableType;
 import javax.persistence.metamodel.ManagedType;
@@ -34,6 +36,7 @@ import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -49,9 +52,9 @@ import org.springframework.util.ClassUtils;
 public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSupport<T, ID> {
 
 	private final IdMetadata<T> idMetadata;
-	private final SingularAttribute<? super T, ?> versionAttribute;
+	private final Optional<SingularAttribute<? super T, ?>> versionAttribute;
 	private final Metamodel metamodel;
-	private final String entityName;
+	private final @Nullable String entityName;
 
 	/**
 	 * Creates a new {@link JpaMetamodelEntityInformation} for the given domain class and {@link Metamodel}.
@@ -101,11 +104,11 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 	 * @return
 	 */
 	@SuppressWarnings("unchecked")
-	private static <T> SingularAttribute<? super T, ?> findVersionAttribute(IdentifiableType<T> type,
+	private static <T> Optional<SingularAttribute<? super T, ?>> findVersionAttribute(IdentifiableType<T> type,
 			Metamodel metamodel) {
 
 		try {
-			return type.getVersion(Object.class);
+			return Optional.ofNullable(type.getVersion(Object.class));
 		} catch (IllegalArgumentException o_O) {
 			// Needs workarounds as the method is implemented with a strict type check on e.g. Hibernate < 4.3
 		}
@@ -114,7 +117,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 
 		for (SingularAttribute<? super T, ?> attribute : attributes) {
 			if (attribute.isVersion()) {
-				return attribute;
+				return Optional.of(attribute);
 			}
 		}
 
@@ -125,13 +128,13 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 			ManagedType<?> managedSuperType = metamodel.managedType(superType);
 
 			if (!(managedSuperType instanceof IdentifiableType)) {
-				return null;
+				return Optional.empty();
 			}
 
-			return (SingularAttribute<? super T, ?>) findVersionAttribute((IdentifiableType<T>) managedSuperType, metamodel);
+			return findVersionAttribute((IdentifiableType<T>) managedSuperType, metamodel);
 
 		} catch (IllegalArgumentException o_O) {
-			return null;
+			return Optional.empty();
 		}
 	}
 
@@ -139,6 +142,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.core.EntityInformation#getId(java.lang.Object)
 	 */
+	@Nullable
 	@SuppressWarnings("unchecked")
 	public ID getId(T entity) {
 
@@ -222,14 +226,14 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 	@Override
 	public boolean isNew(T entity) {
 
-		if (versionAttribute == null || versionAttribute.getJavaType().isPrimitive()) {
+		if (!versionAttribute.isPresent()
+				|| versionAttribute.map(Attribute::getJavaType).map(Class::isPrimitive).orElse(false)) {
 			return super.isNew(entity);
 		}
 
 		BeanWrapper wrapper = new DirectFieldAccessFallbackBeanWrapper(entity);
-		Object versionValue = wrapper.getPropertyValue(versionAttribute.getName());
 
-		return versionValue == null;
+		return versionAttribute.map(it -> wrapper.getPropertyValue(it.getName()) == null).orElse(true);
 	}
 
 	/**
@@ -242,14 +246,15 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 
 		private final IdentifiableType<T> type;
 		private final Set<SingularAttribute<? super T, ?>> attributes;
-		private Class<?> idType;
+		private @Nullable Class<?> idType;
 
 		@SuppressWarnings("unchecked")
 		public IdMetadata(IdentifiableType<T> source) {
 
 			this.type = source;
 			this.attributes = (Set<SingularAttribute<? super T, ?>>) (source.hasSingleIdAttribute()
-					? Collections.singleton(source.getId(source.getIdType().getJavaType())) : source.getIdClassAttributes());
+					? Collections.singleton(source.getId(source.getIdType().getJavaType()))
+					: source.getIdClassAttributes());
 		}
 
 		public boolean hasSimpleId() {
@@ -265,9 +270,14 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 			// lazy initialization of idType field with tolerable benign data-race
 			this.idType = tryExtractIdTypeWithFallbackToIdTypeLookup();
 
+			if (this.idType == null) {
+				throw new IllegalStateException("Cannot resolve Id type from " + type);
+			}
+
 			return this.idType;
 		}
 
+		@Nullable
 		private Class<?> tryExtractIdTypeWithFallbackToIdTypeLookup() {
 
 			try {
@@ -279,6 +289,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 			}
 		}
 
+		@Nullable
 		private static Class<?> fallbackIdTypeLookup(IdentifiableType<?> type) {
 
 			IdClass annotation = AnnotationUtils.findAnnotation(type.getJavaType(), IdClass.class);
@@ -309,7 +320,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 
 		private final Metamodel metamodel;
 
-		public IdentifierDerivingDirectFieldAccessFallbackBeanWrapper(Class<?> type, Metamodel metamodel) {
+		IdentifierDerivingDirectFieldAccessFallbackBeanWrapper(Class<?> type, Metamodel metamodel) {
 			super(type);
 			this.metamodel = metamodel;
 		}
@@ -320,7 +331,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 		 */
 		@Override
 		@SuppressWarnings("unchecked")
-		public void setPropertyValue(String propertyName, Object value) {
+		public void setPropertyValue(String propertyName, @Nullable Object value) {
 
 			if (!isIdentifierDerivationNecessary(value)) {
 				super.setPropertyValue(propertyName, value);
@@ -335,7 +346,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 			if (!nestedEntityInformation.getJavaType().isAnnotationPresent(IdClass.class)) {
 
 				Object nestedIdPropertyValue = new DirectFieldAccessFallbackBeanWrapper(value)
-						.getPropertyValue(nestedEntityInformation.getIdAttribute().getName());
+						.getPropertyValue(nestedEntityInformation.getRequiredIdAttribute().getName());
 				super.setPropertyValue(propertyName, nestedIdPropertyValue);
 				return;
 			}
@@ -354,6 +365,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 			super.setPropertyValue(propertyName, targetIdClassTypeWrapper.getWrappedInstance());
 		}
 
+		@Nullable
 		private Object extractActualIdPropertyValue(BeanWrapper sourceIdValueWrapper, String idAttributeName) {
 
 			Object idPropertyValue = sourceIdValueWrapper.getPropertyValue(idAttributeName);
@@ -391,7 +403,7 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 		 * @return {@literal true} if the given value is not {@literal null} and a mapped persistable entity otherwise
 		 *         {@literal false}
 		 */
-		private boolean isIdentifierDerivationNecessary(Object value) {
+		private boolean isIdentifierDerivationNecessary(@Nullable Object value) {
 
 			if (value == null) {
 				return false;
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/JpaPersistableEntityInformation.java b/src/main/java/org/springframework/data/jpa/repository/support/JpaPersistableEntityInformation.java
index 8bf352f67..4282cb92e 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/JpaPersistableEntityInformation.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/JpaPersistableEntityInformation.java
@@ -18,12 +18,14 @@ package org.springframework.data.jpa.repository.support;
 import javax.persistence.metamodel.Metamodel;
 
 import org.springframework.data.domain.Persistable;
+import org.springframework.lang.Nullable;
 
 /**
  * Extension of {@link JpaMetamodelEntityInformation} that consideres methods of {@link Persistable} to lookup the id.
  * 
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public class JpaPersistableEntityInformation<T extends Persistable<ID>, ID>
 		extends JpaMetamodelEntityInformation<T, ID> {
@@ -51,6 +53,7 @@ public class JpaPersistableEntityInformation<T extends Persistable<ID>, ID>
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation#getId(java.lang.Object)
 	 */
+	@Nullable
 	@Override
 	public ID getId(T entity) {
 		return entity.getId();
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java b/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java
index 86b26e86b..f67262628 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java
@@ -33,6 +33,7 @@ import org.springframework.data.repository.core.support.RepositoryFactorySupport
 import org.springframework.data.repository.query.EvaluationContextProvider;
 import org.springframework.data.repository.query.QueryLookupStrategy;
 import org.springframework.data.repository.query.QueryLookupStrategy.Key;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -133,7 +134,7 @@ public class JpaRepositoryFactory extends RepositoryFactorySupport {
 	 * @see org.springframework.data.repository.core.support.RepositoryFactorySupport#getQueryLookupStrategy(org.springframework.data.repository.query.QueryLookupStrategy.Key, org.springframework.data.repository.query.EvaluationContextProvider)
 	 */
 	@Override
-	protected Optional<QueryLookupStrategy> getQueryLookupStrategy(Key key,
+	protected Optional<QueryLookupStrategy> getQueryLookupStrategy(@Nullable Key key,
 			EvaluationContextProvider evaluationContextProvider) {
 		return Optional.of(JpaQueryLookupStrategy.create(entityManager, key, extractor, evaluationContextProvider));
 	}
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBean.java b/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBean.java
index 615c01693..3e45c82ad 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBean.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBean.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2014 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.core.support.RepositoryFactorySupport;
 import org.springframework.data.repository.core.support.TransactionalRepositoryFactoryBeanSupport;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -30,12 +31,13 @@ import org.springframework.util.Assert;
  * 
  * @author Oliver Gierke
  * @author Eberhard Wolff
+ * @author Mark Paluch
  * @param <T> the type of the repository
  */
 public class JpaRepositoryFactoryBean<T extends Repository<S, ID>, S, ID>
 		extends TransactionalRepositoryFactoryBeanSupport<T, S, ID> {
 
-	private EntityManager entityManager;
+	private @Nullable EntityManager entityManager;
 
 	/**
 	 * Creates a new {@link JpaRepositoryFactoryBean} for the given repository interface.
@@ -73,6 +75,11 @@ public class JpaRepositoryFactoryBean<T extends Repository<S, ID>, S, ID>
 	 */
 	@Override
 	protected RepositoryFactorySupport doCreateRepositoryFactory() {
+
+		if (entityManager == null) {
+			throw new IllegalStateException("EntityManager must not be null!");
+		}
+
 		return createRepositoryFactory(entityManager);
 	}
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/Querydsl.java b/src/main/java/org/springframework/data/jpa/repository/support/Querydsl.java
index 6c14c1bd9..d14859263 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/Querydsl.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/Querydsl.java
@@ -125,7 +125,7 @@ public class Querydsl {
 	 */
 	public <T> JPQLQuery<T> applySorting(Sort sort, JPQLQuery<T> query) {
 
-		if (sort == null) {
+		if (sort.isUnsorted()) {
 			return query;
 		}
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepository.java b/src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepository.java
index 08022382e..509bfb591 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepository.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepository.java
@@ -32,6 +32,7 @@ import org.springframework.data.querydsl.QSort;
 import org.springframework.data.querydsl.QuerydslPredicateExecutor;
 import org.springframework.data.querydsl.SimpleEntityPathResolver;
 import org.springframework.data.repository.support.PageableExecutionUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 import com.querydsl.core.NonUniqueResultException;
@@ -160,7 +161,7 @@ public class QuerydslJpaRepository<T, ID extends Serializable> extends SimpleJpa
 		final JPQLQuery<?> countQuery = createCountQuery(predicate);
 		JPQLQuery<T> query = querydsl.applyPagination(pageable, createQuery(predicate).select(path));
 
-		return PageableExecutionUtils.getPage(query.fetch(), pageable, () -> countQuery.fetchCount());
+		return PageableExecutionUtils.getPage(query.fetch(), pageable, countQuery::fetchCount);
 	}
 
 	/*
@@ -207,13 +208,17 @@ public class QuerydslJpaRepository<T, ID extends Serializable> extends SimpleJpa
 	 * @param predicate, can be {@literal null}.
 	 * @return the Querydsl count {@link JPQLQuery}.
 	 */
-	protected JPQLQuery<?> createCountQuery(Predicate... predicate) {
+	protected JPQLQuery<?> createCountQuery(@Nullable Predicate... predicate) {
 		return doCreateQuery(getQueryHints(), predicate);
 	}
 
-	private AbstractJPAQuery<?, ?> doCreateQuery(QueryHints hints, Predicate... predicate) {
+	private AbstractJPAQuery<?, ?> doCreateQuery(QueryHints hints, @Nullable Predicate... predicate) {
 
-		AbstractJPAQuery<?, ?> query = querydsl.createQuery(path).where(predicate);
+		AbstractJPAQuery<?, ?> query = querydsl.createQuery(path);
+
+		if (predicate != null) {
+			query = query.where(predicate);
+		}
 
 		for (Entry<String, Object> hint : hints) {
 			query.setHint(hint.getKey(), hint.getValue());
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/QuerydslRepositorySupport.java b/src/main/java/org/springframework/data/jpa/repository/support/QuerydslRepositorySupport.java
index dfecce34e..d3c0ac209 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/QuerydslRepositorySupport.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/QuerydslRepositorySupport.java
@@ -15,6 +15,7 @@
  */
 package org.springframework.data.jpa.repository.support;
 
+import javax.annotation.Nullable;
 import javax.annotation.PostConstruct;
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
@@ -42,8 +43,8 @@ public abstract class QuerydslRepositorySupport {
 
 	private final PathBuilder<?> builder;
 
-	private EntityManager entityManager;
-	private Querydsl querydsl;
+	private @Nullable EntityManager entityManager;
+	private @Nullable Querydsl querydsl;
 
 	/**
 	 * Creates a new {@link QuerydslRepositorySupport} instance for the given domain type.
@@ -83,6 +84,7 @@ public abstract class QuerydslRepositorySupport {
 	 * 
 	 * @return the entityManager
 	 */
+	@Nullable
 	protected EntityManager getEntityManager() {
 		return entityManager;
 	}
@@ -94,7 +96,7 @@ public abstract class QuerydslRepositorySupport {
 	 * @return the Querydsl {@link JPQLQuery}.
 	 */
 	protected JPQLQuery<Object> from(EntityPath<?>... paths) {
-		return querydsl.createQuery(paths);
+		return getRequiredQuerydsl().createQuery(paths);
 	}
 
 	/**
@@ -104,7 +106,7 @@ public abstract class QuerydslRepositorySupport {
 	 * @return
 	 */
 	protected <T> JPQLQuery<T> from(EntityPath<T> path) {
-		return querydsl.createQuery(path).select(path);
+		return getRequiredQuerydsl().createQuery(path).select(path);
 	}
 
 	/**
@@ -114,7 +116,7 @@ public abstract class QuerydslRepositorySupport {
 	 * @return the Querydsl {@link DeleteClause}.
 	 */
 	protected DeleteClause<JPADeleteClause> delete(EntityPath<?> path) {
-		return new JPADeleteClause(entityManager, path);
+		return new JPADeleteClause(getRequiredEntityManager(), path);
 	}
 
 	/**
@@ -124,7 +126,7 @@ public abstract class QuerydslRepositorySupport {
 	 * @return the Querydsl {@link UpdateClause}.
 	 */
 	protected UpdateClause<JPAUpdateClause> update(EntityPath<?> path) {
-		return new JPAUpdateClause(entityManager, path);
+		return new JPAUpdateClause(getRequiredEntityManager(), path);
 	}
 
 	/**
@@ -143,7 +145,26 @@ public abstract class QuerydslRepositorySupport {
 	 * 
 	 * @return
 	 */
+	@Nullable
 	protected Querydsl getQuerydsl() {
 		return this.querydsl;
 	}
+
+	private Querydsl getRequiredQuerydsl() {
+
+		if (querydsl == null) {
+			throw new IllegalStateException("Querydsl is null!");
+		}
+
+		return querydsl;
+	}
+
+	private EntityManager getRequiredEntityManager() {
+
+		if (entityManager == null) {
+			throw new IllegalStateException("EntityManager is null!");
+		}
+
+		return entityManager;
+	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java b/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
index 531fffb1a..e039b2430 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java
@@ -53,6 +53,7 @@ import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
 import org.springframework.data.jpa.repository.query.QueryUtils;
 import org.springframework.data.jpa.repository.support.QueryHints.NoHints;
 import org.springframework.data.repository.support.PageableExecutionUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Repository;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.Assert;
@@ -79,7 +80,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	private final EntityManager em;
 	private final PersistenceProvider provider;
 
-	private CrudMethodMetadata metadata;
+	private @Nullable CrudMethodMetadata metadata;
 
 	/**
 	 * Creates a new {@link SimpleJpaRepository} to manage objects of the given {@link JpaEntityInformation}.
@@ -117,7 +118,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 		this.metadata = crudMethodMetadata;
 	}
 
-	protected CrudMethodMetadata getRepositoryMethodMetadata() {
+	protected @Nullable CrudMethodMetadata getRepositoryMethodMetadata() {
 		return metadata;
 	}
 
@@ -301,7 +302,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * @see org.springframework.data.jpa.repository.JpaRepository#findAll()
 	 */
 	public List<T> findAll() {
-		return getQuery(null, (Sort) null).getResultList();
+		return getQuery(null, Sort.unsorted()).getResultList();
 	}
 
 	/*
@@ -310,7 +311,9 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 */
 	public List<T> findAllById(Iterable<ID> ids) {
 
-		if (ids == null || !ids.iterator().hasNext()) {
+		Assert.notNull(ids, "The given Iterable of Id's must not be null!");
+
+		if (!ids.iterator().hasNext()) {
 			return Collections.emptyList();
 		}
 
@@ -326,7 +329,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 		}
 
 		ByIdsSpecification<T> specification = new ByIdsSpecification<T>(entityInformation);
-		TypedQuery<T> query = getQuery(specification, (Sort) null);
+		TypedQuery<T> query = getQuery(specification, Sort.unsorted());
 
 		return query.setParameter(specification.parameter, ids).getResultList();
 	}
@@ -356,10 +359,10 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.JpaSpecificationExecutor#findOne(org.springframework.data.jpa.domain.Specification)
 	 */
-	public Optional<T> findOne(Specification<T> spec) {
+	public Optional<T> findOne(@Nullable Specification<T> spec) {
 
 		try {
-			return Optional.of(getQuery(spec, (Sort) null).getSingleResult());
+			return Optional.of(getQuery(spec, Sort.unsorted()).getSingleResult());
 		} catch (NoResultException e) {
 			return Optional.empty();
 		}
@@ -369,15 +372,15 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.JpaSpecificationExecutor#findAll(org.springframework.data.jpa.domain.Specification)
 	 */
-	public List<T> findAll(Specification<T> spec) {
-		return getQuery(spec, (Sort) null).getResultList();
+	public List<T> findAll(@Nullable Specification<T> spec) {
+		return getQuery(spec, Sort.unsorted()).getResultList();
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.JpaSpecificationExecutor#findAll(org.springframework.data.jpa.domain.Specification, org.springframework.data.domain.Pageable)
 	 */
-	public Page<T> findAll(Specification<T> spec, Pageable pageable) {
+	public Page<T> findAll(@Nullable Specification<T> spec, Pageable pageable) {
 
 		TypedQuery<T> query = getQuery(spec, pageable);
 		return isUnpaged(pageable) ? new PageImpl<T>(query.getResultList())
@@ -388,7 +391,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.JpaSpecificationExecutor#findAll(org.springframework.data.jpa.domain.Specification, org.springframework.data.domain.Sort)
 	 */
-	public List<T> findAll(Specification<T> spec, Sort sort) {
+	public List<T> findAll(@Nullable Specification<T> spec, Sort sort) {
 		return getQuery(spec, sort).getResultList();
 	}
 
@@ -401,7 +404,8 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 
 		try {
 			return Optional
-					.of(getQuery(new ExampleSpecification<S>(example), example.getProbeType(), (Sort) null).getSingleResult());
+					.of(getQuery(new ExampleSpecification<S>(example), example.getProbeType(), Sort.unsorted())
+							.getSingleResult());
 		} catch (NoResultException e) {
 			return Optional.empty();
 		}
@@ -422,7 +426,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 */
 	@Override
 	public <S extends T> boolean exists(Example<S> example) {
-		return !getQuery(new ExampleSpecification<S>(example), example.getProbeType(), (Sort) null).getResultList()
+		return !getQuery(new ExampleSpecification<S>(example), example.getProbeType(), Sort.unsorted()).getResultList()
 				.isEmpty();
 	}
 
@@ -432,7 +436,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 */
 	@Override
 	public <S extends T> List<S> findAll(Example<S> example) {
-		return getQuery(new ExampleSpecification<S>(example), example.getProbeType(), (Sort) null).getResultList();
+		return getQuery(new ExampleSpecification<S>(example), example.getProbeType(), Sort.unsorted()).getResultList();
 	}
 
 	/*
@@ -470,7 +474,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * (non-Javadoc)
 	 * @see org.springframework.data.jpa.repository.JpaSpecificationExecutor#count(org.springframework.data.jpa.domain.Specification)
 	 */
-	public long count(Specification<T> spec) {
+	public long count(@Nullable Specification<T> spec) {
 		return executeCountQuery(getCountQuery(spec, getDomainClass()));
 	}
 
@@ -509,11 +513,9 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	@Transactional
 	public <S extends T> List<S> saveAll(Iterable<S> entities) {
 
-		List<S> result = new ArrayList<S>();
+		Assert.notNull(entities, "The given Iterable of entities not be null!");
 
-		if (entities == null) {
-			return result;
-		}
+		List<S> result = new ArrayList<S>();
 
 		for (S entity : entities) {
 			result.add(save(entity));
@@ -537,12 +539,12 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 *
 	 * @param query must not be {@literal null}.
 	 * @param spec can be {@literal null}.
-	 * @param pageable can be {@literal null}.
+	 * @param pageable must not be {@literal null}.
 	 * @return
 	 * @deprecated use {@link #readPage(TypedQuery, Class, Pageable, Specification)} instead
 	 */
 	@Deprecated
-	protected Page<T> readPage(TypedQuery<T> query, Pageable pageable, Specification<T> spec) {
+	protected Page<T> readPage(TypedQuery<T> query, Pageable pageable, @Nullable Specification<T> spec) {
 		return readPage(query, getDomainClass(), pageable, spec);
 	}
 
@@ -557,7 +559,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * @return
 	 */
 	protected <S extends T> Page<S> readPage(TypedQuery<S> query, final Class<S> domainClass, Pageable pageable,
-			final Specification<S> spec) {
+			@Nullable Specification<S> spec) {
 
 		if (pageable.isPaged()) {
 			query.setFirstResult((int) pageable.getOffset());
@@ -572,12 +574,12 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * Creates a new {@link TypedQuery} from the given {@link Specification}.
 	 *
 	 * @param spec can be {@literal null}.
-	 * @param pageable can be {@literal null}.
+	 * @param pageable must not be {@literal null}.
 	 * @return
 	 */
-	protected TypedQuery<T> getQuery(Specification<T> spec, Pageable pageable) {
+	protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Pageable pageable) {
 
-		Sort sort = pageable == null ? null : pageable.getSort();
+		Sort sort = pageable.isPaged() ? pageable.getSort() : Sort.unsorted();
 		return getQuery(spec, getDomainClass(), sort);
 	}
 
@@ -586,12 +588,13 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 *
 	 * @param spec can be {@literal null}.
 	 * @param domainClass must not be {@literal null}.
-	 * @param pageable can be {@literal null}.
+	 * @param pageable must not be {@literal null}.
 	 * @return
 	 */
-	protected <S extends T> TypedQuery<S> getQuery(Specification<S> spec, Class<S> domainClass, Pageable pageable) {
+	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<S> spec, Class<S> domainClass,
+			Pageable pageable) {
 
-		Sort sort = pageable == null ? null : pageable.getSort();
+		Sort sort = pageable.isPaged() ? pageable.getSort() : Sort.unsorted();
 		return getQuery(spec, domainClass, sort);
 	}
 
@@ -599,10 +602,10 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * Creates a {@link TypedQuery} for the given {@link Specification} and {@link Sort}.
 	 *
 	 * @param spec can be {@literal null}.
-	 * @param sort can be {@literal null}.
+	 * @param sort must not be {@literal null}.
 	 * @return
 	 */
-	protected TypedQuery<T> getQuery(Specification<T> spec, Sort sort) {
+	protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Sort sort) {
 		return getQuery(spec, getDomainClass(), sort);
 	}
 
@@ -611,10 +614,10 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 *
 	 * @param spec can be {@literal null}.
 	 * @param domainClass must not be {@literal null}.
-	 * @param sort can be {@literal null}.
+	 * @param sort must not be {@literal null}.
 	 * @return
 	 */
-	protected <S extends T> TypedQuery<S> getQuery(Specification<S> spec, Class<S> domainClass, Sort sort) {
+	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<S> spec, Class<S> domainClass, Sort sort) {
 
 		CriteriaBuilder builder = em.getCriteriaBuilder();
 		CriteriaQuery<S> query = builder.createQuery(domainClass);
@@ -622,7 +625,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 		Root<S> root = applySpecificationToCriteria(spec, domainClass, query);
 		query.select(root);
 
-		if (sort != null && !sort.isUnsorted()) {
+		if (sort.isSorted()) {
 			query.orderBy(toOrders(sort, root, builder));
 		}
 
@@ -637,7 +640,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * @deprecated override {@link #getCountQuery(Specification, Class)} instead
 	 */
 	@Deprecated
-	protected TypedQuery<Long> getCountQuery(Specification<T> spec) {
+	protected TypedQuery<Long> getCountQuery(@Nullable Specification<T> spec) {
 		return getCountQuery(spec, getDomainClass());
 	}
 
@@ -648,7 +651,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * @param domainClass must not be {@literal null}.
 	 * @return
 	 */
-	protected <S extends T> TypedQuery<Long> getCountQuery(Specification<S> spec, Class<S> domainClass) {
+	protected <S extends T> TypedQuery<Long> getCountQuery(@Nullable Specification<S> spec, Class<S> domainClass) {
 
 		CriteriaBuilder builder = em.getCriteriaBuilder();
 		CriteriaQuery<Long> query = builder.createQuery(Long.class);
@@ -675,7 +678,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	 * @param query must not be {@literal null}.
 	 * @return
 	 */
-	private <S, U extends T> Root<U> applySpecificationToCriteria(Specification<U> spec, Class<U> domainClass,
+	private <S, U extends T> Root<U> applySpecificationToCriteria(@Nullable Specification<U> spec, Class<U> domainClass,
 			CriteriaQuery<S> query) {
 
 		Assert.notNull(domainClass, "Domain class must not be null!");
@@ -739,7 +742,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 	}
 
 	private static boolean isUnpaged(Pageable pageable) {
-		return pageable == null || pageable.isUnpaged();
+		return pageable.isUnpaged();
 	}
 
 	/**
@@ -755,9 +758,9 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 
 		private final JpaEntityInformation<T, ?> entityInformation;
 
-		ParameterExpression<Iterable> parameter;
+		@Nullable ParameterExpression<Iterable> parameter;
 
-		public ByIdsSpecification(JpaEntityInformation<T, ?> entityInformation) {
+		ByIdsSpecification(JpaEntityInformation<T, ?> entityInformation) {
 			this.entityInformation = entityInformation;
 		}
 
@@ -790,7 +793,7 @@ public class SimpleJpaRepository<T, ID> implements JpaRepository<T, ID>, JpaSpec
 		 *
 		 * @param example
 		 */
-		public ExampleSpecification(Example<T> example) {
+		ExampleSpecification(Example<T> example) {
 
 			Assert.notNull(example, "Example must not be null!");
 			this.example = example;
diff --git a/src/main/java/org/springframework/data/jpa/repository/support/package-info.java b/src/main/java/org/springframework/data/jpa/repository/support/package-info.java
index 4dab22453..dbb5bdb2c 100644
--- a/src/main/java/org/springframework/data/jpa/repository/support/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/repository/support/package-info.java
@@ -1,5 +1,7 @@
 /**
  * JPA repository implementations.
  */
+@NonNullApi
 package org.springframework.data.jpa.repository.support;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/support/ClasspathScanningPersistenceUnitPostProcessor.java b/src/main/java/org/springframework/data/jpa/support/ClasspathScanningPersistenceUnitPostProcessor.java
index 7d985225c..3faceffa9 100644
--- a/src/main/java/org/springframework/data/jpa/support/ClasspathScanningPersistenceUnitPostProcessor.java
+++ b/src/main/java/org/springframework/data/jpa/support/ClasspathScanningPersistenceUnitPostProcessor.java
@@ -39,6 +39,7 @@ import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternUtils;
 import org.springframework.core.type.filter.AnnotationTypeFilter;
+import org.springframework.lang.Nullable;
 import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
 import org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor;
 import org.springframework.util.Assert;
@@ -51,6 +52,7 @@ import org.springframework.util.StringUtils;
  * 
  * @author Oliver Gierke
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public class ClasspathScanningPersistenceUnitPostProcessor
 		implements PersistenceUnitPostProcessor, ResourceLoaderAware, EnvironmentAware {
@@ -62,7 +64,7 @@ public class ClasspathScanningPersistenceUnitPostProcessor
 	private ResourcePatternResolver mappingFileResolver = new PathMatchingResourcePatternResolver();
 	private Environment environment = new StandardEnvironment();
 	private ResourceLoader resourceLoader = new DefaultResourceLoader();
-	private String mappingFileNamePattern;
+	private @Nullable String mappingFileNamePattern;
 
 	/**
 	 * Creates a new {@link ClasspathScanningPersistenceUnitPostProcessor} using the given base package as scan base.
@@ -125,7 +127,10 @@ public class ClasspathScanningPersistenceUnitPostProcessor
 		for (BeanDefinition definition : provider.findCandidateComponents(basePackage)) {
 
 			LOG.debug("Registering classpath-scanned entity {} in persistence unit info!", definition.getBeanClassName());
-			pui.addManagedClassName(definition.getBeanClassName());
+
+			if (definition.getBeanClassName() != null) {
+				pui.addManagedClassName(definition.getBeanClassName());
+			}
 		}
 
 		for (String location : scanForMappingFileLocations()) {
diff --git a/src/main/java/org/springframework/data/jpa/support/MergingPersistenceUnitManager.java b/src/main/java/org/springframework/data/jpa/support/MergingPersistenceUnitManager.java
index 48b636967..e57db0b18 100644
--- a/src/main/java/org/springframework/data/jpa/support/MergingPersistenceUnitManager.java
+++ b/src/main/java/org/springframework/data/jpa/support/MergingPersistenceUnitManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2013 the original author or authors.
+ * Copyright 2011-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,7 +46,7 @@ public class MergingPersistenceUnitManager extends DefaultPersistenceUnitManager
 		// Invoke normal post processing
 		super.postProcessPersistenceUnitInfo(pui);
 
-		PersistenceUnitInfo oldPui = getPersistenceUnitInfo(pui.getPersistenceUnitName());
+		PersistenceUnitInfo oldPui = getPersistenceUnitInfo(((PersistenceUnitInfo) pui).getPersistenceUnitName());
 
 		if (oldPui != null) {
 			postProcessPersistenceUnitInfo(pui, oldPui);
diff --git a/src/main/java/org/springframework/data/jpa/support/package-info.java b/src/main/java/org/springframework/data/jpa/support/package-info.java
index 1a2b61924..b37b9ad9a 100644
--- a/src/main/java/org/springframework/data/jpa/support/package-info.java
+++ b/src/main/java/org/springframework/data/jpa/support/package-info.java
@@ -1,5 +1,7 @@
 /**
  * Various helper classes useful when working with JPA.
  */
+@NonNullApi
 package org.springframework.data.jpa.support;
 
+import org.springframework.lang.NonNullApi;
diff --git a/src/main/java/org/springframework/data/jpa/util/BeanDefinitionUtils.java b/src/main/java/org/springframework/data/jpa/util/BeanDefinitionUtils.java
index c54a8e499..dea8e71c7 100644
--- a/src/main/java/org/springframework/data/jpa/util/BeanDefinitionUtils.java
+++ b/src/main/java/org/springframework/data/jpa/util/BeanDefinitionUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,7 @@ import org.springframework.util.ClassUtils;
  * Utility methods to work with {@link BeanDefinition} instances from {@link BeanFactoryPostProcessor}s.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  */
 public class BeanDefinitionUtils {
 
@@ -127,8 +128,10 @@ public class BeanDefinitionUtils {
 			if (!EntityManagerFactory.class.getName().equals(definition.getPropertyValues().get("expectedType"))) {
 				return;
 			}
-		} else if (beanFactory.getType(name) == null
-				|| !EntityManagerFactory.class.isAssignableFrom(beanFactory.getType(name))) {
+		}
+
+		Class<?> type = beanFactory.getType(name);
+		if (type == null || !EntityManagerFactory.class.isAssignableFrom(type)) {
 			return;
 		}
 
diff --git a/src/main/java/org/springframework/data/jpa/util/JpaMetamodel.java b/src/main/java/org/springframework/data/jpa/util/JpaMetamodel.java
index 4d9bbe820..1b8023a1b 100644
--- a/src/main/java/org/springframework/data/jpa/util/JpaMetamodel.java
+++ b/src/main/java/org/springframework/data/jpa/util/JpaMetamodel.java
@@ -18,6 +18,7 @@ package org.springframework.data.jpa.util;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.Optional;
 import java.util.Set;
 
 import javax.persistence.metamodel.ManagedType;
@@ -29,12 +30,13 @@ import org.springframework.util.Assert;
  * Wrapper around the JPA {@link Metamodel} to be able to apply some fixes against bugs in provider implementations.
  * 
  * @author Oliver Gierke
+ * @author Mark Paluch
  */
 public class JpaMetamodel {
 
 	private final Metamodel metamodel;
 
-	private Collection<Class<?>> managedTypes;
+	private Optional<Collection<Class<?>>> managedTypes = Optional.empty();
 
 	/**
 	 * Creates a new {@link JpaMetamodel} for the given JPA {@link Metamodel}.
@@ -70,24 +72,23 @@ public class JpaMetamodel {
 	 */
 	private Collection<Class<?>> getManagedTypes() {
 
-		if (managedTypes != null) {
-			return managedTypes;
-		}
+		if (!managedTypes.isPresent()) {
 
-		Set<ManagedType<?>> managedTypes = metamodel.getManagedTypes();
-		Set<Class<?>> types = new HashSet<Class<?>>(managedTypes.size());
+			Set<ManagedType<?>> managedTypes = metamodel.getManagedTypes();
+			Set<Class<?>> types = new HashSet<Class<?>>(managedTypes.size());
 
-		for (ManagedType<?> managedType : metamodel.getManagedTypes()) {
+			for (ManagedType<?> managedType : metamodel.getManagedTypes()) {
 
-			Class<?> type = managedType.getJavaType();
+				Class<?> type = managedType.getJavaType();
 
-			if (type != null) {
-				types.add(type);
+				if (type != null) {
+					types.add(type);
+				}
 			}
+
+			this.managedTypes = Optional.of(Collections.unmodifiableSet(types));
 		}
 
-		this.managedTypes = Collections.unmodifiableSet(types);
-
-		return this.managedTypes;
+		return this.managedTypes.get();
 	}
 }
diff --git a/src/main/java/org/springframework/data/jpa/util/package-info.java b/src/main/java/org/springframework/data/jpa/util/package-info.java
new file mode 100644
index 000000000..e374512f9
--- /dev/null
+++ b/src/main/java/org/springframework/data/jpa/util/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Spring Data JPA utilities.
+ */
+@NonNullApi
+package org.springframework.data.jpa.util;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/test/java/org/springframework/data/jpa/domain/JpaSortTests.java b/src/test/java/org/springframework/data/jpa/domain/JpaSortTests.java
index 75c9a6254..04f269e2e 100644
--- a/src/test/java/org/springframework/data/jpa/domain/JpaSortTests.java
+++ b/src/test/java/org/springframework/data/jpa/domain/JpaSortTests.java
@@ -35,6 +35,7 @@ import org.springframework.data.jpa.domain.sample.Address_;
 import org.springframework.data.jpa.domain.sample.MailMessage_;
 import org.springframework.data.jpa.domain.sample.MailSender_;
 import org.springframework.data.jpa.domain.sample.User_;
+import org.springframework.lang.Nullable;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 
@@ -52,10 +53,10 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 @ContextConfiguration("classpath:infrastructure.xml")
 public class JpaSortTests {
 
-	private static final Attribute<?, ?> NULL_ATTRIBUTE = null;
+	private static final @Nullable Attribute<?, ?> NULL_ATTRIBUTE = null;
 	private static final Attribute<?, ?>[] EMPTY_ATTRIBUTES = new Attribute<?, ?>[0];
 
-	private static final PluralAttribute<?, ?, ?> NULL_PLURAL_ATTRIBUTE = null;
+	private static final @Nullable PluralAttribute<?, ?, ?> NULL_PLURAL_ATTRIBUTE = null;
 	private static final PluralAttribute<?, ?, ?>[] EMPTY_PLURAL_ATTRIBUTES = new PluralAttribute<?, ?, ?>[0];
 
 	@Test(expected = IllegalArgumentException.class) // DATAJPA-12
diff --git a/src/test/java/org/springframework/data/jpa/domain/sample/AuditableUser.java b/src/test/java/org/springframework/data/jpa/domain/sample/AuditableUser.java
index 5eef4acce..a7bae73c5 100644
--- a/src/test/java/org/springframework/data/jpa/domain/sample/AuditableUser.java
+++ b/src/test/java/org/springframework/data/jpa/domain/sample/AuditableUser.java
@@ -15,7 +15,6 @@
  */
 package org.springframework.data.jpa.domain.sample;
 
-import java.time.Instant;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -25,11 +24,12 @@ import javax.persistence.ManyToMany;
 import javax.persistence.NamedQuery;
 
 import org.springframework.data.jpa.domain.AbstractAuditable;
+import org.springframework.lang.Nullable;
 
 /**
  * Sample auditable user to demonstrate working with {@code AbstractAuditableEntity}. No declaration of an ID is
  * necessary. Furthermore no auditing information has to be declared explicitly.
- * 
+ *
  * @author Oliver Gierke
  * @author Thomas Darimont
  */
@@ -41,24 +41,25 @@ public class AuditableUser extends AbstractAuditable<AuditableUser, Integer> {
 
 	private String firstname;
 
-	@ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE }) private Set<AuditableRole> roles = new HashSet<AuditableRole>();
+	@ManyToMany(
+			cascade = { CascadeType.PERSIST, CascadeType.MERGE }) private final Set<AuditableRole> roles = new HashSet<>();
 
 	public AuditableUser() {
 		this(null);
 	}
 
-	public AuditableUser(Integer id) {
+	public AuditableUser(@Nullable Integer id) {
 		this(id, null);
 	}
 
-	public AuditableUser(Integer id, String firstname) {
+	public AuditableUser(@Nullable Integer id, String firstname) {
 		setId(id);
 		this.firstname = firstname;
 	}
 
 	/**
 	 * Returns the firstname.
-	 * 
+	 *
 	 * @return the firstname
 	 */
 	public String getFirstname() {
@@ -68,7 +69,7 @@ public class AuditableUser extends AbstractAuditable<AuditableUser, Integer> {
 
 	/**
 	 * Sets the firstname.
-	 * 
+	 *
 	 * @param firstname the firstname to set
 	 */
 	public void setFirstname(final String firstname) {
diff --git a/src/test/java/org/springframework/data/jpa/domain/support/AuditingEntityListenerTests.java b/src/test/java/org/springframework/data/jpa/domain/support/AuditingEntityListenerTests.java
index b5f19e01a..ea07a4689 100644
--- a/src/test/java/org/springframework/data/jpa/domain/support/AuditingEntityListenerTests.java
+++ b/src/test/java/org/springframework/data/jpa/domain/support/AuditingEntityListenerTests.java
@@ -18,7 +18,6 @@ package org.springframework.data.jpa.domain.support;
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
-import java.time.Instant;
 import java.time.LocalDateTime;
 import java.util.Optional;
 
@@ -40,7 +39,7 @@ import org.springframework.transaction.annotation.Transactional;
 
 /**
  * Integration test for {@link AuditingEntityListener}.
- * 
+ *
  * @author Oliver Gierke
  */
 @RunWith(SpringJUnit4ClassRunner.class)
diff --git a/src/test/java/org/springframework/data/jpa/repository/EclipseLinkNamespaceUserRepositoryTests.java b/src/test/java/org/springframework/data/jpa/repository/EclipseLinkNamespaceUserRepositoryTests.java
index d86e36b87..30792c8f8 100644
--- a/src/test/java/org/springframework/data/jpa/repository/EclipseLinkNamespaceUserRepositoryTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/EclipseLinkNamespaceUserRepositoryTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2014 the original author or authors.
+ * Copyright 2008-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,14 +43,6 @@ public class EclipseLinkNamespaceUserRepositoryTests extends NamespaceUserReposi
 
 	}
 
-	/**
-	 * Ignored until https://bugs.eclipse.org/bugs/show_bug.cgi?id=349477 is resolved.
-	 */
-	@Override
-	public void allowsExecutingPageableMethodWithNullPageable() {
-
-	}
-
 	/**
 	 * Ignored until https://bugs.eclipse.org/bugs/show_bug.cgi?id=349477 is resolved.
 	 */
diff --git a/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java b/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
index feffde7e5..6a356f94d 100644
--- a/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java
@@ -161,11 +161,6 @@ public class UserRepositoryTests {
 				secondUser, thirdUser);
 	}
 
-	@Test
-	public void savingNullCollectionIsNoOp() throws Exception {
-		assertThat(repository.saveAll(null)).isEmpty();
-	}
-
 	@Test
 	public void savingEmptyCollectionIsNoOp() throws Exception {
 		assertThat(repository.saveAll(new ArrayList<>())).isEmpty();
@@ -536,7 +531,7 @@ public class UserRepositoryTests {
 	public void returnsSameListIfNoSortIsGiven() throws Exception {
 
 		flushTestUsers();
-		assertSameElements(repository.findAll((Sort) null), repository.findAll());
+		assertSameElements(repository.findAll(Sort.unsorted()), repository.findAll());
 	}
 
 	@Test
@@ -552,7 +547,7 @@ public class UserRepositoryTests {
 	public void returnsAllAsPageIfNoPageableIsGiven() throws Exception {
 
 		flushTestUsers();
-		assertThat(repository.findAll((Pageable) null)).isEqualTo(new PageImpl<User>(repository.findAll()));
+		assertThat(repository.findAll(Pageable.unpaged())).isEqualTo(new PageImpl<>(repository.findAll()));
 	}
 
 	@Test
@@ -569,7 +564,7 @@ public class UserRepositoryTests {
 	@Test
 	public void executesPagedSpecificationsCorrectly() throws Exception {
 
-		Page<User> result = executeSpecWithSort(null);
+		Page<User> result = executeSpecWithSort(Sort.unsorted());
 		assertThat(result.getContent()).isSubsetOf(firstUser, thirdUser);
 	}
 
@@ -758,17 +753,17 @@ public class UserRepositoryTests {
 	}
 
 	@Test // DATAJPA-201
-	public void allowsExecutingPageableMethodWithNullPageable() {
+	public void allowsExecutingPageableMethodWithUnpagedArgument() {
 
 		flushTestUsers();
 
 		assertThat(repository.findByFirstname("Oliver", null)).containsOnly(firstUser);
 
-		Page<User> page = repository.findByFirstnameIn(null, "Oliver");
+		Page<User> page = repository.findByFirstnameIn(Pageable.unpaged(), "Oliver");
 		assertThat(page.getNumberOfElements()).isEqualTo(1);
 		assertThat(page.getContent()).contains(firstUser);
 
-		page = repository.findAll((Pageable) null);
+		page = repository.findAll(Pageable.unpaged());
 		assertThat(page.getNumberOfElements()).isEqualTo(4);
 		assertThat(page.getContent()).contains(firstUser, secondUser, thirdUser, fourthUser);
 	}
@@ -868,6 +863,7 @@ public class UserRepositoryTests {
 		flushTestUsers();
 
 		Page<User> page = repository.findAll(new Specification<User>() {
+			@Override
 			public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
 				return cb.equal(root.get("lastname"), "Gierke");
 			}
@@ -941,11 +937,10 @@ public class UserRepositoryTests {
 		assertThat(repository.existsByLastname("Hans Peter")).isEqualTo(false);
 	}
 
-	@Test // DATAJPA-332
+	@Test // DATAJPA-332, DATAJPA-1168
 	public void findAllReturnsEmptyIterableIfNoIdsGiven() {
 
 		assertThat(repository.findAllById(Collections.<Integer> emptySet())).isEmpty();
-		assertThat(repository.findAllById((Iterable<Integer>) null)).isEmpty();
 	}
 
 	@Test // DATAJPA-391
@@ -1171,7 +1166,7 @@ public class UserRepositoryTests {
 
 		flushTestUsers();
 
-		List<User> result = repository.findByAttributesIn(new HashSet<String>(Arrays.asList("cool", "hip")));
+		List<User> result = repository.findByAttributesIn(new HashSet<>(Arrays.asList("cool", "hip")));
 
 		assertThat(result).containsOnly(firstUser, secondUser);
 	}
@@ -1230,7 +1225,7 @@ public class UserRepositoryTests {
 
 		flushTestUsers();
 
-		byte[] result = null; // repository.findBinaryDataByIdJpaQl(firstUser.getId());
+		byte[] result = repository.findBinaryDataByIdNative(firstUser.getId());
 
 		assertThat(result.length).isEqualTo(data.length);
 		assertThat(result).isEqualTo(data);
@@ -1640,7 +1635,7 @@ public class UserRepositoryTests {
 
 		Stream<User> stream = repository.findAllByCustomQueryAndStream();
 
-		final List<User> users = new ArrayList<User>();
+		final List<User> users = new ArrayList<>();
 
 		try {
 
@@ -1666,7 +1661,7 @@ public class UserRepositoryTests {
 
 		Stream<User> stream = repository.readAllByFirstnameNotNull();
 
-		final List<User> users = new ArrayList<User>();
+		final List<User> users = new ArrayList<>();
 
 		try {
 
@@ -1692,7 +1687,7 @@ public class UserRepositoryTests {
 
 		Stream<User> stream = repository.streamAllPaged(PageRequest.of(0, 2));
 
-		final List<User> users = new ArrayList<User>();
+		final List<User> users = new ArrayList<>();
 
 		try {
 
diff --git a/src/test/java/org/springframework/data/jpa/repository/config/CustomRepositoryFactoryConfigTests.java b/src/test/java/org/springframework/data/jpa/repository/config/CustomRepositoryFactoryConfigTests.java
index e8c37d4ac..62e8b35e3 100644
--- a/src/test/java/org/springframework/data/jpa/repository/config/CustomRepositoryFactoryConfigTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/config/CustomRepositoryFactoryConfigTests.java
@@ -26,7 +26,6 @@ import org.springframework.data.jpa.repository.custom.UserCustomExtendedReposito
 import org.springframework.data.jpa.repository.support.TransactionalRepositoryTests.DelegatingTransactionManager;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
-import org.springframework.util.Assert;
 
 /**
  * Annotation to exclude repository interfaces from being picked up and thus in consequence getting an instance being
@@ -36,7 +35,7 @@ import org.springframework.util.Assert;
  * custom repository base class to implement methods declared in that intermediate interface. In this case you typically
  * derive your concrete repository interfaces from the intermediate one but don't want to create a Spring bean for the
  * intermediate interface.
- * 
+ *
  * @author Oliver Gierke
  * @author Mark Paluch
  */
@@ -44,11 +43,9 @@ import org.springframework.util.Assert;
 @ContextConfiguration(locations = "classpath:config/namespace-customfactory-context.xml")
 public class CustomRepositoryFactoryConfigTests {
 
-	@Autowired(required = false)
-	UserCustomExtendedRepository userRepository;
+	@Autowired(required = false) UserCustomExtendedRepository userRepository;
 
-	@Autowired
-	DelegatingTransactionManager transactionManager;
+	@Autowired DelegatingTransactionManager transactionManager;
 
 	@Before
 	public void setup() {
diff --git a/src/test/java/org/springframework/data/jpa/repository/custom/package-info.java b/src/test/java/org/springframework/data/jpa/repository/custom/package-info.java
new file mode 100644
index 000000000..054f40763
--- /dev/null
+++ b/src/test/java/org/springframework/data/jpa/repository/custom/package-info.java
@@ -0,0 +1,4 @@
+@NonNullApi
+package org.springframework.data.jpa.repository.custom;
+
+import org.springframework.lang.NonNullApi;
diff --git a/src/test/java/org/springframework/data/jpa/repository/query/Jpa21UtilsTests.java b/src/test/java/org/springframework/data/jpa/repository/query/Jpa21UtilsTests.java
index 6a2e43066..500dd985d 100644
--- a/src/test/java/org/springframework/data/jpa/repository/query/Jpa21UtilsTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/query/Jpa21UtilsTests.java
@@ -35,6 +35,7 @@ import org.springframework.transaction.annotation.Transactional;
 
 /**
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration("classpath:application-context.xml")
@@ -91,7 +92,7 @@ public class Jpa21UtilsTests {
 		assertThat(colleagues, terminatesGraphWith("roles"));
 		assertThat(colleagues, hasSubgraphs("colleagues"));
 
-		AttributeNode colleaguesOfColleagues = findNode("colleagues", colleagues);
+		AttributeNode<?> colleaguesOfColleagues = findNode("colleagues", colleagues);
 		assertThat(colleaguesOfColleagues, terminatesGraphWith("roles"));
 	}
 
@@ -111,7 +112,7 @@ public class Jpa21UtilsTests {
 		assertThat(colleagues, terminatesGraphWith("roles"));
 		assertThat(colleagues, hasSubgraphs("colleagues"));
 
-		AttributeNode colleaguesOfColleagues = findNode("colleagues", colleagues);
+		AttributeNode<?> colleaguesOfColleagues = findNode("colleagues", colleagues);
 		assertThat(colleaguesOfColleagues, terminatesGraphWith("roles"));
 	}
 
@@ -131,7 +132,7 @@ public class Jpa21UtilsTests {
 		assertThat(colleagues, terminatesGraphWith("roles"));
 		assertThat(colleagues, hasSubgraphs("colleagues"));
 
-		AttributeNode colleaguesOfColleagues = findNode("colleagues", colleagues);
+		AttributeNode<?> colleaguesOfColleagues = findNode("colleagues", colleagues);
 		assertThat(colleaguesOfColleagues, terminatesGraphWith("roles"));
 	}
 
diff --git a/src/test/java/org/springframework/data/jpa/repository/query/StringQueryUnitTests.java b/src/test/java/org/springframework/data/jpa/repository/query/StringQueryUnitTests.java
index d4fe165bd..bd4cb711f 100644
--- a/src/test/java/org/springframework/data/jpa/repository/query/StringQueryUnitTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/query/StringQueryUnitTests.java
@@ -26,12 +26,11 @@ import org.junit.rules.ExpectedException;
 import org.springframework.data.jpa.repository.query.StringQuery.InParameterBinding;
 import org.springframework.data.jpa.repository.query.StringQuery.LikeParameterBinding;
 import org.springframework.data.jpa.repository.query.StringQuery.ParameterBinding;
-import org.springframework.data.repository.query.Param;
 import org.springframework.data.repository.query.parser.Part.Type;
 
 /**
  * Unit tests for {@link StringQuery}.
- * 
+ *
  * @author Oliver Gierke
  * @author Thomas Darimont
  */
@@ -281,7 +280,8 @@ public class StringQueryUnitTests {
 	}
 
 	/**
-	 * @see <a href="download.oracle.com/otn-pub/jcp/persistence-2_1-fr-eval-spec/JavaPersistence.pdf">JPA 2.1 specification, section 4.8</a>
+	 * @see <a href="download.oracle.com/otn-pub/jcp/persistence-2_1-fr-eval-spec/JavaPersistence.pdf">JPA 2.1
+	 *      specification, section 4.8</a>
 	 */
 	@Test // DATAJPA-886
 	public void detectsConstructorExpressionForDefaultConstructor() {
diff --git a/src/test/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBeanUnitTests.java b/src/test/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBeanUnitTests.java
index 87f34f1d2..71181c65b 100644
--- a/src/test/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBeanUnitTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactoryBeanUnitTests.java
@@ -22,7 +22,6 @@ import static org.mockito.Mockito.*;
 import java.io.Serializable;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Optional;
 
 import javax.persistence.EntityManager;
 import javax.persistence.metamodel.Metamodel;
diff --git a/src/test/java/org/springframework/data/jpa/util/IsAttributeNode.java b/src/test/java/org/springframework/data/jpa/util/IsAttributeNode.java
index 63e76fa62..a9f3baedc 100644
--- a/src/test/java/org/springframework/data/jpa/util/IsAttributeNode.java
+++ b/src/test/java/org/springframework/data/jpa/util/IsAttributeNode.java
@@ -25,18 +25,20 @@ import javax.persistence.Subgraph;
 
 import org.hamcrest.Description;
 import org.hamcrest.TypeSafeMatcher;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
 
 /**
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 
 	private boolean terminatingNodeCheck = false;
 	private List<String> nodes;
 	private List<String> subgraphs;
-	private List<String> errors = new ArrayList<String>();
+	private final List<String> errors = new ArrayList<>();
 
 	@Override
 	protected boolean matchesSafely(AttributeNode<T> item) {
@@ -129,7 +131,7 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 * @param graph
 	 * @return
 	 */
-	public static AttributeNode<?> findNode(String nodeName, EntityGraph<?> graph) {
+	public static AttributeNode<?> findNode(String nodeName, @Nullable EntityGraph<?> graph) {
 
 		if (graph == null) {
 			return null;
@@ -145,6 +147,7 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 * @param nodes
 	 * @return
 	 */
+	@Nullable
 	public static AttributeNode<?> findNode(String nodeName, List<AttributeNode<?>> nodes) {
 
 		if (CollectionUtils.isEmpty(nodes)) {
@@ -168,6 +171,7 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 * @param node
 	 * @return
 	 */
+	@Nullable
 	public static AttributeNode<?> findNode(String attributeName, AttributeNode<?> node) {
 
 		if (CollectionUtils.isEmpty(node.getSubgraphs())) {
@@ -180,7 +184,7 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 
 	private List<String> extractExistingAttributeNames(Subgraph<?> graph) {
 
-		List<String> result = new ArrayList<String>(graph.getAttributeNodes().size());
+		List<String> result = new ArrayList<>(graph.getAttributeNodes().size());
 		for (AttributeNode<?> node : graph.getAttributeNodes()) {
 			result.add(node.getAttributeName());
 		}
@@ -193,9 +197,9 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 * @param nodeNames
 	 * @return
 	 */
-	public static IsAttributeNode terminatesGraphWith(String... nodeNames) {
+	public static <T> IsAttributeNode<T> terminatesGraphWith(String... nodeNames) {
 
-		IsAttributeNode matcher = new IsAttributeNode();
+		IsAttributeNode<T> matcher = new IsAttributeNode<>();
 		matcher.nodes = Arrays.asList(nodeNames);
 		return matcher;
 	}
@@ -206,9 +210,9 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 *
 	 * @return
 	 */
-	public static IsAttributeNode hasSubgraphs(String... subgraphNames) {
+	public static <T> IsAttributeNode<T> hasSubgraphs(String... subgraphNames) {
 
-		IsAttributeNode matcher = new IsAttributeNode();
+		IsAttributeNode<T> matcher = new IsAttributeNode<>();
 		matcher.subgraphs = Arrays.asList(subgraphNames);
 		return matcher;
 	}
@@ -219,9 +223,9 @@ public class IsAttributeNode<T> extends TypeSafeMatcher<AttributeNode<T>> {
 	 *
 	 * @return
 	 */
-	public static IsAttributeNode terminatesGraph() {
+	public static <T> IsAttributeNode<T> terminatesGraph() {
 
-		IsAttributeNode matcher = new IsAttributeNode();
+		IsAttributeNode<T> matcher = new IsAttributeNode<>();
 		matcher.terminatingNodeCheck = true;
 		return matcher;
 	}