diff --git a/src/main/java/org/springframework/data/keyvalue/core/IterableConverter.java b/src/main/java/org/springframework/data/keyvalue/core/IterableConverter.java
index 23527eb..5a32b3d 100644
--- a/src/main/java/org/springframework/data/keyvalue/core/IterableConverter.java
+++ b/src/main/java/org/springframework/data/keyvalue/core/IterableConverter.java
@@ -20,6 +20,9 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+import org.springframework.lang.Contract;
+
 /**
  * Converter capable of transforming a given {@link Iterable} into a collection type.
  *
@@ -36,7 +39,12 @@ public final class IterableConverter {
 	 * @param source
 	 * @return {@link Collections#emptyList()} when source is {@literal null}.
 	 */
-	public static <T> List<T> toList(Iterable<T> source) {
+	@Contract("_ -> !null")
+	public static <T> List<T> toList(@Nullable Iterable<T> source) {
+
+		if(source == null) {
+			return Collections.emptyList();
+		}
 
 		if (source instanceof List) {
 			return (List<T>) source;
diff --git a/src/main/java/org/springframework/data/keyvalue/core/PredicateQueryEngine.java b/src/main/java/org/springframework/data/keyvalue/core/PredicateQueryEngine.java
index b8bb755..1577a7a 100644
--- a/src/main/java/org/springframework/data/keyvalue/core/PredicateQueryEngine.java
+++ b/src/main/java/org/springframework/data/keyvalue/core/PredicateQueryEngine.java
@@ -24,6 +24,7 @@ import java.util.stream.Stream;
 
 import org.jspecify.annotations.Nullable;
 import org.springframework.data.keyvalue.core.query.KeyValueQuery;
+import org.springframework.lang.Contract;
 
 /**
  * {@link QueryEngine} implementation specific for executing {@link Predicate} based {@link KeyValueQuery} against
@@ -78,6 +79,7 @@ public class PredicateQueryEngine extends QueryEngine<KeyValueAdapter, Predicate
 		return filterMatchingRange(tmp, criteria, offset, rows);
 	}
 
+	@Contract("!null, _, _, _ -> !null")
 	private static <S> List<S> filterMatchingRange(List<S> source, @Nullable Predicate<?> criteria, long offset, int rows) {
 
 		Stream<S> stream = source.stream();
diff --git a/src/main/java/org/springframework/data/keyvalue/core/PropertyPathComparator.java b/src/main/java/org/springframework/data/keyvalue/core/PropertyPathComparator.java
index ff28cb3..ce2c121 100644
--- a/src/main/java/org/springframework/data/keyvalue/core/PropertyPathComparator.java
+++ b/src/main/java/org/springframework/data/keyvalue/core/PropertyPathComparator.java
@@ -21,6 +21,7 @@ import java.util.Map;
 
 import org.jspecify.annotations.Nullable;
 import org.springframework.data.mapping.PropertyPath;
+import org.springframework.lang.Contract;
 
 /**
  * {@link Comparator} implementation to compare objects based on a {@link PropertyPath}. This comparator obtains the
@@ -81,6 +82,7 @@ public class PropertyPathComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public PropertyPathComparator<@Nullable T> asc() {
 		this.asc = true;
 		return this;
@@ -91,6 +93,7 @@ public class PropertyPathComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public PropertyPathComparator<@Nullable T> desc() {
 		this.asc = false;
 		return this;
@@ -101,6 +104,7 @@ public class PropertyPathComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public PropertyPathComparator<@Nullable T> nullsFirst() {
 		this.nullsFirst = true;
 		return this;
@@ -111,6 +115,7 @@ public class PropertyPathComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public PropertyPathComparator<@Nullable T> nullsLast() {
 		this.nullsFirst = false;
 		return this;
diff --git a/src/main/java/org/springframework/data/keyvalue/core/SpelPropertyComparator.java b/src/main/java/org/springframework/data/keyvalue/core/SpelPropertyComparator.java
index 3aafcf0..5e3d4d1 100644
--- a/src/main/java/org/springframework/data/keyvalue/core/SpelPropertyComparator.java
+++ b/src/main/java/org/springframework/data/keyvalue/core/SpelPropertyComparator.java
@@ -21,6 +21,7 @@ import org.jspecify.annotations.Nullable;
 import org.springframework.expression.spel.standard.SpelExpression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.SimpleEvaluationContext;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 
 /**
@@ -63,6 +64,7 @@ public class SpelPropertyComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public SpelPropertyComparator<@Nullable T> asc() {
 		this.asc = true;
 		return this;
@@ -73,6 +75,7 @@ public class SpelPropertyComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public SpelPropertyComparator<@Nullable T> desc() {
 		this.asc = false;
 		return this;
@@ -83,6 +86,7 @@ public class SpelPropertyComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public SpelPropertyComparator<@Nullable T> nullsFirst() {
 		this.nullsFirst = true;
 		return this;
@@ -93,6 +97,7 @@ public class SpelPropertyComparator<T> implements Comparator<T> {
 	 *
 	 * @return
 	 */
+	@Contract("-> this")
 	public SpelPropertyComparator<@Nullable T> nullsLast() {
 		this.nullsFirst = false;
 		return this;
diff --git a/src/main/java/org/springframework/data/keyvalue/core/query/KeyValueQuery.java b/src/main/java/org/springframework/data/keyvalue/core/query/KeyValueQuery.java
index 0cf1a3f..9931d45 100644
--- a/src/main/java/org/springframework/data/keyvalue/core/query/KeyValueQuery.java
+++ b/src/main/java/org/springframework/data/keyvalue/core/query/KeyValueQuery.java
@@ -17,6 +17,7 @@ package org.springframework.data.keyvalue.core.query;
 
 import org.jspecify.annotations.Nullable;
 import org.springframework.data.domain.Sort;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 
 /**
@@ -143,6 +144,7 @@ public class KeyValueQuery<T> {
 	 * @param sort must not be {@literal null}.
 	 * @return
 	 */
+	@Contract("_ -> this")
 	public KeyValueQuery<T> orderBy(Sort sort) {
 
 		Assert.notNull(sort, "Sort must not be null");
@@ -161,6 +163,7 @@ public class KeyValueQuery<T> {
 	 * @param offset
 	 * @return
 	 */
+	@Contract("_ -> this")
 	public KeyValueQuery<T> skip(long offset) {
 
 		setOffset(offset);
@@ -173,6 +176,7 @@ public class KeyValueQuery<T> {
 	 * @param rows
 	 * @return
 	 */
+	@Contract("_ -> this")
 	public KeyValueQuery<T> limit(int rows) {
 		setRows(rows);
 		return this;
diff --git a/src/main/java/org/springframework/data/keyvalue/repository/query/PredicateQueryCreator.java b/src/main/java/org/springframework/data/keyvalue/repository/query/PredicateQueryCreator.java
index a1b6361..efb4ff9 100644
--- a/src/main/java/org/springframework/data/keyvalue/repository/query/PredicateQueryCreator.java
+++ b/src/main/java/org/springframework/data/keyvalue/repository/query/PredicateQueryCreator.java
@@ -35,6 +35,7 @@ import org.springframework.data.repository.query.parser.AbstractQueryCreator;
 import org.springframework.data.repository.query.parser.Part;
 import org.springframework.data.repository.query.parser.Part.IgnoreCaseType;
 import org.springframework.data.repository.query.parser.PartTree;
+import org.springframework.lang.Contract;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -124,7 +125,8 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 			return new ValueComparingPredicate(part.getProperty(), false);
 		}
 
-		public Predicate<Object> isEqualTo(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> isEqualTo(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> {
 
 				if (!ObjectUtils.nullSafeEquals(IgnoreCaseType.NEVER, part.shouldIgnoreCase())) {
@@ -145,22 +147,27 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 			return isNull().negate();
 		}
 
-		public Predicate<Object> isLessThan(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> isLessThan(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> comparator().compare(o, value) < 0);
 		}
 
-		public Predicate<Object> isLessThanEqual(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> isLessThanEqual(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> comparator().compare(o, value) <= 0);
 		}
 
-		public Predicate<Object> isGreaterThan(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> isGreaterThan(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> comparator().compare(o, value) > 0);
 		}
 
-		public Predicate<Object> isGreaterThanEqual(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> isGreaterThanEqual(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> comparator().compare(o, value) >= 0);
 		}
 
+		@Contract("!null -> new")
 		public Predicate<Object> matches(Pattern pattern) {
 
 			return new ValueComparingPredicate(part.getProperty(), o -> {
@@ -172,7 +179,8 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 			});
 		}
 
-		public Predicate<Object> matches(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> matches(@Nullable Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> {
 
 				if (o == null || value == null) {
@@ -188,10 +196,12 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 			});
 		}
 
+		@Contract("!null -> new")
 		public Predicate<Object> matches(String regex) {
 			return matches(Pattern.compile(regex));
 		}
 
+		@Contract("!null -> new")
 		public Predicate<Object> in(Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> {
 
@@ -207,11 +217,11 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 					return ObjectUtils.containsElement(ObjectUtils.toObjectArray(value), value);
 				}
 				return false;
-
 			});
 		}
 
-		public Predicate<Object> contains(Object value) {
+		@Contract("_ -> new")
+		public Predicate<Object> contains(@Nullable Object value) {
 
 			return new ValueComparingPredicate(part.getProperty(), o -> {
 
@@ -245,6 +255,7 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 			});
 		}
 
+		@Contract("!null -> new")
 		public Predicate<Object> startsWith(Object value) {
 			return new ValueComparingPredicate(part.getProperty(), o -> {
 
@@ -261,6 +272,7 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 
 		}
 
+		@Contract("!null -> new")
 		public Predicate<Object> endsWith(Object value) {
 
 			return new ValueComparingPredicate(part.getProperty(), o -> {
@@ -281,13 +293,13 @@ public class PredicateQueryCreator extends AbstractQueryCreator<KeyValueQuery<Pr
 	static class ValueComparingPredicate implements Predicate<Object> {
 
 		private final PropertyPath path;
-		private final Function<Object, Boolean> check;
+		private final Function<@Nullable Object, Boolean> check;
 
-		public ValueComparingPredicate(PropertyPath path, Object expected) {
+		public ValueComparingPredicate(PropertyPath path, @Nullable Object expected) {
 			this(path, (value) -> ObjectUtils.nullSafeEquals(value, expected));
 		}
 
-		public ValueComparingPredicate(PropertyPath path, Function<Object, Boolean> check) {
+		public ValueComparingPredicate(PropertyPath path, Function<@Nullable Object, Boolean> check) {
 			this.path = path;
 			this.check = check;
 		}
diff --git a/src/main/java/org/springframework/data/keyvalue/repository/support/KeyValueQuerydslUtils.java b/src/main/java/org/springframework/data/keyvalue/repository/support/KeyValueQuerydslUtils.java
index e2d256b..7e41e3d 100644
--- a/src/main/java/org/springframework/data/keyvalue/repository/support/KeyValueQuerydslUtils.java
+++ b/src/main/java/org/springframework/data/keyvalue/repository/support/KeyValueQuerydslUtils.java
@@ -22,6 +22,7 @@ import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Order;
 import org.springframework.data.mapping.PropertyPath;
 import org.springframework.data.querydsl.QSort;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 
 import com.querydsl.core.types.Expression;
@@ -52,6 +53,7 @@ abstract class KeyValueQuerydslUtils {
 	 * @param builder must not be {@literal null}.
 	 * @return empty {@code OrderSpecifier<?>[]} when sort is {@literal null}.
 	 */
+	@Contract("!null, !null -> new")
 	static OrderSpecifier<?>[] toOrderSpecifier(Sort sort, PathBuilder<?> builder) {
 
 		Assert.notNull(sort, "Sort must not be null");