@Nullable all the way: null-safety at field level

This commits extends nullability declarations to the field level, formalizing the interaction between methods and their underlying fields and therefore avoiding any nullability mismatch.

Issue: SPR-15720

spring-context/src/main/java/org/springframework/cache/Cache.java

@@ -169,6 +169,7 @@ public interface Cache {
 	@SuppressWarnings("serial")
 	class ValueRetrievalException extends RuntimeException {
 
+		@Nullable
 		private final Object key;
 
 		public ValueRetrievalException(@Nullable Object key, Callable<?> loader, Throwable ex) {

spring-context/src/main/java/org/springframework/cache/annotation/AbstractCachingConfiguration.java

@@ -27,6 +27,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportAware;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -41,14 +42,19 @@ import org.springframework.util.CollectionUtils;
 @Configuration
 public abstract class AbstractCachingConfiguration implements ImportAware {
 
+	@Nullable
 	protected AnnotationAttributes enableCaching;
 
+	@Nullable
 	protected CacheManager cacheManager;
 
+	@Nullable
 	protected CacheResolver cacheResolver;
 
+	@Nullable
 	protected KeyGenerator keyGenerator;
 
+	@Nullable
 	protected CacheErrorHandler errorHandler;
 
 

spring-context/src/main/java/org/springframework/cache/annotation/ProxyCachingConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -44,7 +44,9 @@ public class ProxyCachingConfiguration extends AbstractCachingConfiguration {
 				new BeanFactoryCacheOperationSourceAdvisor();
 		advisor.setCacheOperationSource(cacheOperationSource());
 		advisor.setAdvice(cacheInterceptor());
-		advisor.setOrder(this.enableCaching.<Integer>getNumber("order"));
+		if (this.enableCaching != null) {
+			advisor.setOrder(this.enableCaching.<Integer>getNumber("order"));
+		}
 		return advisor;
 	}
 

spring-context/src/main/java/org/springframework/cache/annotation/SpringCacheAnnotationParser.java

@@ -263,12 +263,16 @@ public class SpringCacheAnnotationParser implements CacheAnnotationParser, Seria
 	 */
 	static class DefaultCacheConfig {
 
+		@Nullable
 		private final String[] cacheNames;
 
+		@Nullable
 		private final String keyGenerator;
 
+		@Nullable
 		private final String cacheManager;
 
+		@Nullable
 		private final String cacheResolver;
 
 		public DefaultCacheConfig() {

spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCache.java

@@ -52,6 +52,7 @@ public class ConcurrentMapCache extends AbstractValueAdaptingCache {
 
 	private final ConcurrentMap<Object, Object> store;
 
+	@Nullable
 	private final SerializationDelegate serialization;
 
 
@@ -176,7 +177,7 @@ public class ConcurrentMapCache extends AbstractValueAdaptingCache {
 		Object storeValue = super.toStoreValue(userValue);
 		if (this.serialization != null) {
 			try {
-				return serializeValue(storeValue);
+				return serializeValue(this.serialization, storeValue);
 			}
 			catch (Throwable ex) {
 				throw new IllegalArgumentException("Failed to serialize cache value '" + userValue +
@@ -188,10 +189,10 @@ public class ConcurrentMapCache extends AbstractValueAdaptingCache {
 		}
 	}
 
-	private Object serializeValue(Object storeValue) throws IOException {
+	private Object serializeValue(SerializationDelegate serialization, Object storeValue) throws IOException {
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
 		try {
-			this.serialization.serialize(storeValue, out);
+			serialization.serialize(storeValue, out);
 			return out.toByteArray();
 		}
 		finally {
@@ -203,7 +204,7 @@ public class ConcurrentMapCache extends AbstractValueAdaptingCache {
 	protected Object fromStoreValue(Object storeValue) {
 		if (this.serialization != null) {
 			try {
-				return super.fromStoreValue(deserializeValue(storeValue));
+				return super.fromStoreValue(deserializeValue(this.serialization, storeValue));
 			}
 			catch (Throwable ex) {
 				throw new IllegalArgumentException("Failed to deserialize cache value '" + storeValue + "'", ex);
@@ -215,10 +216,10 @@ public class ConcurrentMapCache extends AbstractValueAdaptingCache {
 
 	}
 
-	private Object deserializeValue(Object storeValue) throws IOException {
+	private Object deserializeValue(SerializationDelegate serialization, Object storeValue) throws IOException {
 		ByteArrayInputStream in = new ByteArrayInputStream((byte[]) storeValue);
 		try {
-			return this.serialization.deserialize(in);
+			return serialization.deserialize(in);
 		}
 		finally {
 			in.close();

spring-context/src/main/java/org/springframework/cache/concurrent/ConcurrentMapCacheFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -21,6 +21,7 @@ import java.util.concurrent.ConcurrentMap;
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -41,10 +42,12 @@ public class ConcurrentMapCacheFactoryBean
 
 	private String name = "";
 
+	@Nullable
 	private ConcurrentMap<Object, Object> store;
 
 	private boolean allowNullValues = true;
 
+	@Nullable
 	private ConcurrentMapCache cache;
 
 

spring-context/src/main/java/org/springframework/cache/config/CacheAdviceParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -197,7 +197,8 @@ class CacheAdviceParser extends AbstractSingleBeanDefinitionParser {
 
 		private String method;
 
-		private String[] caches = null;
+		@Nullable
+		private String[] caches;
 
 		Props(Element root) {
 			String defaultCache = root.getAttribute("cache");
@@ -220,12 +221,12 @@ class CacheAdviceParser extends AbstractSingleBeanDefinitionParser {
 			if (StringUtils.hasText(cache)) {
 				localCaches = StringUtils.commaDelimitedListToStringArray(cache.trim());
 			}
-			else {
-				if (this.caches == null) {
-					readerCtx.error("No cache specified for " + element.getNodeName(), element);
-				}
+			if (localCaches != null) {
+				builder.setCacheNames(localCaches);
+			}
+			else {
+				readerCtx.error("No cache specified for " + element.getNodeName(), element);
 			}
-			builder.setCacheNames(localCaches);
 
 			builder.setKey(getAttributeValue(element, "key", this.key));
 			builder.setKeyGenerator(getAttributeValue(element, "key-generator", this.keyGenerator));
@@ -233,8 +234,8 @@ class CacheAdviceParser extends AbstractSingleBeanDefinitionParser {
 			builder.setCondition(getAttributeValue(element, "condition", this.condition));
 
 			if (StringUtils.hasText(builder.getKey()) && StringUtils.hasText(builder.getKeyGenerator())) {
-				throw new IllegalStateException("Invalid cache advice configuration on '"
-						+ element.toString() + "'. Both 'key' and 'keyGenerator' attributes have been set. " +
+				throw new IllegalStateException("Invalid cache advice configuration on '" +
+						element.toString() + "'. Both 'key' and 'keyGenerator' attributes have been set. " +
 						"These attributes are mutually exclusive: either set the SpEL expression used to" +
 						"compute the key at runtime or set the name of the KeyGenerator bean to use.");
 			}

spring-context/src/main/java/org/springframework/cache/interceptor/CacheProxyFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2012 the original author or authors.
+ * Copyright 2010-2017 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.
@@ -35,6 +35,7 @@ import org.springframework.aop.support.DefaultPointcutAdvisor;
  * of the Spring reference documentation for more information.
  *
  * @author Costin Leau
+ * @author Juergen Hoeller
  * @since 3.1
  * @see org.springframework.aop.framework.ProxyFactoryBean
  * @see CacheInterceptor
@@ -44,9 +45,16 @@ public class CacheProxyFactoryBean extends AbstractSingletonProxyFactoryBean {
 
 	private final CacheInterceptor cachingInterceptor = new CacheInterceptor();
 
-	private Pointcut pointcut;
+	private Pointcut pointcut = Pointcut.TRUE;
 
 
+	/**
+	 * Set the sources used to find cache operations.
+	 */
+	public void setCacheOperationSources(CacheOperationSource... cacheOperationSources) {
+		this.cachingInterceptor.setCacheOperationSources(cacheOperationSources);
+	}
+
 	/**
 	 * Set a pointcut, i.e a bean that can cause conditional invocation
 	 * of the CacheInterceptor depending on method and attributes passed.
@@ -58,21 +66,11 @@ public class CacheProxyFactoryBean extends AbstractSingletonProxyFactoryBean {
 		this.pointcut = pointcut;
 	}
 
+
 	@Override
 	protected Object createMainInterceptor() {
 		this.cachingInterceptor.afterPropertiesSet();
-		if (this.pointcut == null) {
-			// Rely on default pointcut.
-			throw new UnsupportedOperationException();
-		}
 		return new DefaultPointcutAdvisor(this.pointcut, this.cachingInterceptor);
 	}
 
-	/**
-	 * Set the sources used to find cache operations.
-	 */
-	public void setCacheOperationSources(CacheOperationSource... cacheOperationSources) {
-		this.cachingInterceptor.setCacheOperationSources(cacheOperationSources);
-	}
-
 }

spring-context/src/main/java/org/springframework/cache/support/SimpleValueWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -28,6 +28,7 @@ import org.springframework.lang.Nullable;
  */
 public class SimpleValueWrapper implements ValueWrapper {
 
+	@Nullable
 	private final Object value;
 
 

spring-context/src/main/java/org/springframework/context/annotation/ClassPathBeanDefinitionScanner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -66,6 +66,7 @@ public class ClassPathBeanDefinitionScanner extends ClassPathScanningCandidateCo
 
 	private BeanDefinitionDefaults beanDefinitionDefaults = new BeanDefinitionDefaults();
 
+	@Nullable
 	private String[] autowireCandidatePatterns;
 
 	private BeanNameGenerator beanNameGenerator = new AnnotationBeanNameGenerator();

spring-context/src/main/java/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.java

@@ -42,6 +42,7 @@ import org.springframework.core.env.EnvironmentCapable;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
+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.AnnotationMetadata;
@@ -97,14 +98,19 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 
 	private final List<TypeFilter> excludeFilters = new LinkedList<>();
 
+	@Nullable
 	private Environment environment;
 
+	@Nullable
 	private ConditionEvaluator conditionEvaluator;
 
+	@Nullable
 	private ResourcePatternResolver resourcePatternResolver;
 
+	@Nullable
 	private MetadataReaderFactory metadataReaderFactory;
 
+	@Nullable
 	private CandidateComponentsIndex componentsIndex;
 
 
@@ -232,6 +238,9 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 
 	@Override
 	public final Environment getEnvironment() {
+		if (this.environment == null) {
+			this.environment = new StandardEnvironment();
+		}
 		return this.environment;
 	}
 
@@ -262,6 +271,13 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * Return the ResourceLoader that this component provider uses.
 	 */
 	public final ResourceLoader getResourceLoader() {
+		return getResourcePatternResolver();
+	}
+
+	private ResourcePatternResolver getResourcePatternResolver() {
+		if (this.resourcePatternResolver == null) {
+			this.resourcePatternResolver = new PathMatchingResourcePatternResolver();
+		}
 		return this.resourcePatternResolver;
 	}
 
@@ -280,6 +296,9 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * Return the MetadataReaderFactory used by this component provider.
 	 */
 	public final MetadataReaderFactory getMetadataReaderFactory() {
+		if (this.metadataReaderFactory == null) {
+			this.metadataReaderFactory = new CachingMetadataReaderFactory();
+		}
 		return this.metadataReaderFactory;
 	}
 
@@ -290,8 +309,8 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * @return a corresponding Set of autodetected bean definitions
 	 */
 	public Set<BeanDefinition> findCandidateComponents(String basePackage) {
-		if (isIndexSupported()) {
-			return addCandidateComponentsFromIndex(basePackage);
+		if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
+			return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
 		}
 		else {
 			return scanCandidateComponents(basePackage);
@@ -304,12 +323,9 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * instance is supported by it, {@code false} otherwise
 	 * @since 5.0
 	 */
-	protected boolean isIndexSupported() {
-		if (this.componentsIndex == null) {
-			return false;
-		}
+	private boolean indexSupportsIncludeFilters() {
 		for (TypeFilter includeFilter : this.includeFilters) {
-			if (!isIndexSupportsIncludeFilter(includeFilter)) {
+			if (!indexSupportsIncludeFilter(includeFilter)) {
 				return false;
 			}
 		}
@@ -323,7 +339,7 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * @since 5.0
 	 * @see #extractStereotype(TypeFilter)
 	 */
-	protected boolean isIndexSupportsIncludeFilter(TypeFilter filter) {
+	private boolean indexSupportsIncludeFilter(TypeFilter filter) {
 		if (filter instanceof AnnotationTypeFilter) {
 			Class<? extends Annotation> annotation = ((AnnotationTypeFilter) filter).getAnnotationType();
 			return (AnnotationUtils.isAnnotationDeclaredLocally(Indexed.class, annotation) ||
@@ -341,10 +357,10 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * @param filter the filter to handle
 	 * @return the stereotype in the index matching this filter
 	 * @since 5.0
-	 * @see #isIndexSupportsIncludeFilter(TypeFilter)
+	 * @see #indexSupportsIncludeFilter(TypeFilter)
 	 */
 	@Nullable
-	protected String extractStereotype(TypeFilter filter) {
+	private String extractStereotype(TypeFilter filter) {
 		if (filter instanceof AnnotationTypeFilter) {
 			return ((AnnotationTypeFilter) filter).getAnnotationType().getName();
 		}
@@ -354,7 +370,7 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 		return null;
 	}
 
-	private Set<BeanDefinition> addCandidateComponentsFromIndex(String basePackage) {
+	private Set<BeanDefinition> addCandidateComponentsFromIndex(CandidateComponentsIndex index, String basePackage) {
 		Set<BeanDefinition> candidates = new LinkedHashSet<>();
 		try {
 			Set<String> types = new HashSet<>();
@@ -363,12 +379,12 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 				if (stereotype == null) {
 					throw new IllegalArgumentException("Failed to extract stereotype from "+ filter);
 				}
-				types.addAll(this.componentsIndex.getCandidateTypes(basePackage, stereotype));
+				types.addAll(index.getCandidateTypes(basePackage, stereotype));
 			}
 			boolean traceEnabled = logger.isTraceEnabled();
 			boolean debugEnabled = logger.isDebugEnabled();
 			for (String type : types) {
-				MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(type);
+				MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(type);
 				if (isCandidateComponent(metadataReader)) {
 					AnnotatedGenericBeanDefinition sbd = new AnnotatedGenericBeanDefinition(
 							metadataReader.getAnnotationMetadata());
@@ -402,7 +418,7 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 		try {
 			String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
 					resolveBasePackage(basePackage) + '/' + this.resourcePattern;
-			Resource[] resources = this.resourcePatternResolver.getResources(packageSearchPath);
+			Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
 			boolean traceEnabled = logger.isTraceEnabled();
 			boolean debugEnabled = logger.isDebugEnabled();
 			for (Resource resource : resources) {
@@ -411,7 +427,7 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 				}
 				if (resource.isReadable()) {
 					try {
-						MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(resource);
+						MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
 						if (isCandidateComponent(metadataReader)) {
 							ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
 							sbd.setResource(resource);
@@ -462,7 +478,7 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 * @return the pattern specification to be used for package searching
 	 */
 	protected String resolveBasePackage(String basePackage) {
-		return ClassUtils.convertClassNameToResourcePath(this.environment.resolveRequiredPlaceholders(basePackage));
+		return ClassUtils.convertClassNameToResourcePath(getEnvironment().resolveRequiredPlaceholders(basePackage));
 	}
 
 	/**
@@ -473,12 +489,12 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 */
 	protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
 		for (TypeFilter tf : this.excludeFilters) {
-			if (tf.match(metadataReader, this.metadataReaderFactory)) {
+			if (tf.match(metadataReader, getMetadataReaderFactory())) {
 				return false;
 			}
 		}
 		for (TypeFilter tf : this.includeFilters) {
-			if (tf.match(metadataReader, this.metadataReaderFactory)) {
+			if (tf.match(metadataReader, getMetadataReaderFactory())) {
 				return isConditionMatch(metadataReader);
 			}
 		}
@@ -493,7 +509,8 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 	 */
 	private boolean isConditionMatch(MetadataReader metadataReader) {
 		if (this.conditionEvaluator == null) {
-			this.conditionEvaluator = new ConditionEvaluator(getRegistry(), getEnvironment(), getResourceLoader());
+			this.conditionEvaluator =
+					new ConditionEvaluator(getRegistry(), this.environment, this.resourcePatternResolver);
 		}
 		return !this.conditionEvaluator.shouldSkip(metadataReader.getAnnotationMetadata());
 	}

spring-context/src/main/java/org/springframework/context/annotation/CommonAnnotationBeanPostProcessor.java

@@ -143,12 +143,11 @@ import org.springframework.util.StringValueResolver;
 public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBeanPostProcessor
 		implements InstantiationAwareBeanPostProcessor, BeanFactoryAware, Serializable {
 
-	// Common Annotations 1.1 Resource.lookup() available? Not present on JDK 6...
-	private static final Method lookupAttribute = ClassUtils.getMethodIfAvailable(Resource.class, "lookup");
+	@Nullable
+	private static Class<? extends Annotation> webServiceRefClass;
 
-	private static Class<? extends Annotation> webServiceRefClass = null;
-
-	private static Class<? extends Annotation> ejbRefClass = null;
+	@Nullable
+	private static Class<? extends Annotation> ejbRefClass;
 
 	static {
 		try {
@@ -180,14 +179,16 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 
 	private transient BeanFactory jndiFactory = new SimpleJndiBeanFactory();
 
+	@Nullable
 	private transient BeanFactory resourceFactory;
 
+	@Nullable
 	private transient BeanFactory beanFactory;
 
+	@Nullable
 	private transient StringValueResolver embeddedValueResolver;
 
-	private transient final Map<String, InjectionMetadata> injectionMetadataCache =
-			new ConcurrentHashMap<>(256);
+	private transient final Map<String, InjectionMetadata> injectionMetadataCache = new ConcurrentHashMap<>(256);
 
 
 	/**
@@ -532,12 +533,13 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 	 */
 	protected abstract class LookupElement extends InjectionMetadata.InjectedElement {
 
-		protected String name;
+		protected String name = "";
 
 		protected boolean isDefaultName = false;
 
-		protected Class<?> lookupType;
+		protected Class<?> lookupType = Object.class;
 
+		@Nullable
 		protected String mappedName;
 
 		public LookupElement(Member member, @Nullable PropertyDescriptor pd) {
@@ -602,10 +604,9 @@ public class CommonAnnotationBeanPostProcessor extends InitDestroyAnnotationBean
 				// No resource type specified... check field/method.
 				resourceType = getResourceType();
 			}
-			this.name = resourceName;
+			this.name = (resourceName != null ? resourceName : "");
 			this.lookupType = resourceType;
-			String lookupValue = (lookupAttribute != null ?
-					(String) ReflectionUtils.invokeMethod(lookupAttribute, resource) : null);
+			String lookupValue = resource.lookup();
 			this.mappedName = (StringUtils.hasLength(lookupValue) ? lookupValue : resource.mappedName());
 			Lazy lazy = ae.getAnnotation(Lazy.class);
 			this.lazyLookup = (lazy != null && lazy.value());

spring-context/src/main/java/org/springframework/context/annotation/ConditionEvaluator.java

@@ -133,14 +133,17 @@ class ConditionEvaluator {
 	 */
 	private static class ConditionContextImpl implements ConditionContext {
 
+		@Nullable
 		private final BeanDefinitionRegistry registry;
 
+		@Nullable
 		private final ConfigurableListableBeanFactory beanFactory;
 
 		private final Environment environment;
 
 		private final ResourceLoader resourceLoader;
 
+		@Nullable
 		private final ClassLoader classLoader;
 
 		public ConditionContextImpl(@Nullable BeanDefinitionRegistry registry,

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassEnhancer.java

@@ -95,7 +95,7 @@ class ConfigurationClassEnhancer {
 	 * container-aware callbacks capable of respecting scoping and other bean semantics.
 	 * @return the enhanced subclass
 	 */
-	public Class<?> enhance(Class<?> configClass, ClassLoader classLoader) {
+	public Class<?> enhance(Class<?> configClass, @Nullable ClassLoader classLoader) {
 		if (EnhancedConfiguration.class.isAssignableFrom(configClass)) {
 			if (logger.isDebugEnabled()) {
 				logger.debug(String.format("Ignoring request to enhance %s as it has " +
@@ -118,7 +118,7 @@ class ConfigurationClassEnhancer {
 	/**
 	 * Creates a new CGLIB {@link Enhancer} instance.
 	 */
-	private Enhancer newEnhancer(Class<?> superclass, ClassLoader classLoader) {
+	private Enhancer newEnhancer(Class<?> superclass, @Nullable ClassLoader classLoader) {
 		Enhancer enhancer = new Enhancer();
 		enhancer.setSuperclass(superclass);
 		enhancer.setInterfaces(new Class<?>[] {EnhancedConfiguration.class});
@@ -210,6 +210,7 @@ class ConfigurationClassEnhancer {
 	 */
 	private static class BeanFactoryAwareGeneratorStrategy extends DefaultGeneratorStrategy {
 
+		@Nullable
 		private final ClassLoader classLoader;
 
 		public BeanFactoryAwareGeneratorStrategy(@Nullable ClassLoader classLoader) {

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassParser.java

@@ -133,6 +133,7 @@ class ConfigurationClassParser {
 
 	private final ImportStack importStack = new ImportStack();
 
+	@Nullable
 	private List<DeferredImportSelectorHolder> deferredImportSelectors;
 
 
@@ -539,8 +540,11 @@ class ConfigurationClassParser {
 	private void processDeferredImportSelectors() {
 		List<DeferredImportSelectorHolder> deferredImports = this.deferredImportSelectors;
 		this.deferredImportSelectors = null;
-		Collections.sort(deferredImports, DEFERRED_IMPORT_COMPARATOR);
+		if (deferredImports == null) {
+			return;
+		}
 
+		Collections.sort(deferredImports, DEFERRED_IMPORT_COMPARATOR);
 		for (DeferredImportSelectorHolder deferredImport : deferredImports) {
 			ConfigurationClass configClass = deferredImport.getConfigurationClass();
 			try {

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -54,6 +54,7 @@ import org.springframework.context.annotation.ConfigurationClassEnhancer.Enhance
 import org.springframework.core.Ordered;
 import org.springframework.core.PriorityOrdered;
 import org.springframework.core.env.Environment;
+import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.type.AnnotationMetadata;
@@ -96,10 +97,12 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 
 	private ProblemReporter problemReporter = new FailFastProblemReporter();
 
+	@Nullable
 	private Environment environment;
 
 	private ResourceLoader resourceLoader = new DefaultResourceLoader();
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	private MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory();
@@ -110,6 +113,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 
 	private final Set<Integer> factoriesPostProcessed = new HashSet<>();
 
+	@Nullable
 	private ConfigurationClassBeanDefinitionReader reader;
 
 	private boolean localBeanNameGeneratorSet = false;
@@ -193,7 +197,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 	}
 
 	@Override
-	public void setResourceLoader(@Nullable ResourceLoader resourceLoader) {
+	public void setResourceLoader(ResourceLoader resourceLoader) {
 		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
 		this.resourceLoader = resourceLoader;
 		if (!this.setMetadataReaderFactoryCalled) {
@@ -297,6 +301,10 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 			}
 		}
 
+		if (this.environment == null) {
+			this.environment = new StandardEnvironment();
+		}
+
 		// Parse each @Configuration class
 		ConfigurationClassParser parser = new ConfigurationClassParser(
 				this.metadataReaderFactory, this.problemReporter, this.environment,

spring-context/src/main/java/org/springframework/context/annotation/LoadTimeWeavingConfiguration.java

@@ -27,6 +27,7 @@ import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.instrument.classloading.LoadTimeWeaver;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * {@code @Configuration} class that registers a {@link LoadTimeWeaver} bean.
@@ -43,10 +44,13 @@ import org.springframework.lang.Nullable;
 @Configuration
 public class LoadTimeWeavingConfiguration implements ImportAware, BeanClassLoaderAware {
 
+	@Nullable
 	private AnnotationAttributes enableLTW;
 
+	@Nullable
 	private LoadTimeWeavingConfigurer ltwConfigurer;
 
+	@Nullable
 	private ClassLoader beanClassLoader;
 
 
@@ -65,7 +69,7 @@ public class LoadTimeWeavingConfiguration implements ImportAware, BeanClassLoade
 	}
 
 	@Override
-	public void setBeanClassLoader(@Nullable ClassLoader beanClassLoader) {
+	public void setBeanClassLoader(ClassLoader beanClassLoader) {
 		this.beanClassLoader = beanClassLoader;
 	}
 
@@ -73,6 +77,7 @@ public class LoadTimeWeavingConfiguration implements ImportAware, BeanClassLoade
 	@Bean(name = ConfigurableApplicationContext.LOAD_TIME_WEAVER_BEAN_NAME)
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	public LoadTimeWeaver loadTimeWeaver() {
+		Assert.state(this.beanClassLoader != null, "No ClassLoader set");
 		LoadTimeWeaver loadTimeWeaver = null;
 
 		if (this.ltwConfigurer != null) {
@@ -85,22 +90,24 @@ public class LoadTimeWeavingConfiguration implements ImportAware, BeanClassLoade
 			loadTimeWeaver = new DefaultContextLoadTimeWeaver(this.beanClassLoader);
 		}
 
-		AspectJWeaving aspectJWeaving = this.enableLTW.getEnum("aspectjWeaving");
-		switch (aspectJWeaving) {
-			case DISABLED:
-				// AJ weaving is disabled -> do nothing
-				break;
-			case AUTODETECT:
-				if (this.beanClassLoader.getResource(AspectJWeavingEnabler.ASPECTJ_AOP_XML_RESOURCE) == null) {
-					// No aop.xml present on the classpath -> treat as 'disabled'
+		if (this.enableLTW != null) {
+			AspectJWeaving aspectJWeaving = this.enableLTW.getEnum("aspectjWeaving");
+			switch (aspectJWeaving) {
+				case DISABLED:
+					// AJ weaving is disabled -> do nothing
 					break;
-				}
-				// aop.xml is present on the classpath -> enable
-				AspectJWeavingEnabler.enableAspectJWeaving(loadTimeWeaver, this.beanClassLoader);
-				break;
-			case ENABLED:
-				AspectJWeavingEnabler.enableAspectJWeaving(loadTimeWeaver, this.beanClassLoader);
-				break;
+				case AUTODETECT:
+					if (this.beanClassLoader.getResource(AspectJWeavingEnabler.ASPECTJ_AOP_XML_RESOURCE) == null) {
+						// No aop.xml present on the classpath -> treat as 'disabled'
+						break;
+					}
+					// aop.xml is present on the classpath -> enable
+					AspectJWeavingEnabler.enableAspectJWeaving(loadTimeWeaver, this.beanClassLoader);
+					break;
+				case ENABLED:
+					AspectJWeavingEnabler.enableAspectJWeaving(loadTimeWeaver, this.beanClassLoader);
+					break;
+			}
 		}
 
 		return loadTimeWeaver;

spring-context/src/main/java/org/springframework/context/annotation/MBeanExportConfiguration.java

@@ -33,6 +33,7 @@ import org.springframework.jmx.support.RegistrationPolicy;
 import org.springframework.jmx.support.WebSphereMBeanServerFactoryBean;
 import org.springframework.jndi.JndiLocatorDelegate;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
@@ -52,10 +53,13 @@ public class MBeanExportConfiguration implements ImportAware, EnvironmentAware,
 
 	private static final String MBEAN_EXPORTER_BEAN_NAME = "mbeanExporter";
 
+	@Nullable
 	private AnnotationAttributes enableMBeanExport;
 
+	@Nullable
 	private Environment environment;
 
+	@Nullable
 	private BeanFactory beanFactory;
 
 
@@ -84,14 +88,15 @@ public class MBeanExportConfiguration implements ImportAware, EnvironmentAware,
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	public AnnotationMBeanExporter mbeanExporter() {
 		AnnotationMBeanExporter exporter = new AnnotationMBeanExporter();
-		setupDomain(exporter);
-		setupServer(exporter);
-		setupRegistrationPolicy(exporter);
+		Assert.state(this.enableMBeanExport != null, "No EnableMBeanExport annotation found");
+		setupDomain(exporter, this.enableMBeanExport);
+		setupServer(exporter, this.enableMBeanExport);
+		setupRegistrationPolicy(exporter, this.enableMBeanExport);
 		return exporter;
 	}
 
-	private void setupDomain(AnnotationMBeanExporter exporter) {
-		String defaultDomain = this.enableMBeanExport.getString("defaultDomain");
+	private void setupDomain(AnnotationMBeanExporter exporter, AnnotationAttributes enableMBeanExport) {
+		String defaultDomain = enableMBeanExport.getString("defaultDomain");
 		if (StringUtils.hasLength(defaultDomain) && this.environment != null) {
 			defaultDomain = this.environment.resolvePlaceholders(defaultDomain);
 		}
@@ -100,12 +105,13 @@ public class MBeanExportConfiguration implements ImportAware, EnvironmentAware,
 		}
 	}
 
-	private void setupServer(AnnotationMBeanExporter exporter) {
-		String server = this.enableMBeanExport.getString("server");
+	private void setupServer(AnnotationMBeanExporter exporter, AnnotationAttributes enableMBeanExport) {
+		String server = enableMBeanExport.getString("server");
 		if (StringUtils.hasLength(server) && this.environment != null) {
 			server = this.environment.resolvePlaceholders(server);
 		}
 		if (StringUtils.hasText(server)) {
+			Assert.state(this.beanFactory != null, "No BeanFactory set");
 			exporter.setServer(this.beanFactory.getBean(server, MBeanServer.class));
 		}
 		else {
@@ -119,8 +125,8 @@ public class MBeanExportConfiguration implements ImportAware, EnvironmentAware,
 		}
 	}
 
-	private void setupRegistrationPolicy(AnnotationMBeanExporter exporter) {
-		RegistrationPolicy registrationPolicy = this.enableMBeanExport.getEnum("registration");
+	private void setupRegistrationPolicy(AnnotationMBeanExporter exporter, AnnotationAttributes enableMBeanExport) {
+		RegistrationPolicy registrationPolicy = enableMBeanExport.getEnum("registration");
 		exporter.setRegistrationPolicy(registrationPolicy);
 	}
 

spring-context/src/main/java/org/springframework/context/event/AbstractApplicationEventMulticaster.java

@@ -65,8 +65,10 @@ public abstract class AbstractApplicationEventMulticaster
 
 	final Map<ListenerCacheKey, ListenerRetriever> retrieverCache = new ConcurrentHashMap<>(64);
 
+	@Nullable
 	private ClassLoader beanClassLoader;
 
+	@Nullable
 	private BeanFactory beanFactory;
 
 	private Object retrievalMutex = this.defaultRetriever;
@@ -300,6 +302,7 @@ public abstract class AbstractApplicationEventMulticaster
 
 		private final ResolvableType eventType;
 
+		@Nullable
 		private final Class<?> sourceType;
 
 		public ListenerCacheKey(ResolvableType eventType, @Nullable Class<?> sourceType) {

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -71,14 +71,17 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 
 	private final List<ResolvableType> declaredEventTypes;
 
+	@Nullable
 	private final String condition;
 
 	private final int order;
 
 	private final AnnotatedElementKey methodKey;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
+	@Nullable
 	private EventExpressionEvaluator evaluator;
 
 
@@ -291,6 +294,7 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 	 * annotation or any matching attribute on a composed annotation that
 	 * is meta-annotated with {@code @EventListener}.
 	 */
+	@Nullable
 	protected String getCondition() {
 		return this.condition;
 	}

spring-context/src/main/java/org/springframework/context/event/EventPublicationInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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 +25,8 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * {@link MethodInterceptor Interceptor} that publishes an
@@ -48,8 +50,10 @@ import org.springframework.context.ApplicationEventPublisherAware;
 public class EventPublicationInterceptor
 		implements MethodInterceptor, ApplicationEventPublisherAware, InitializingBean {
 
+	@Nullable
 	private Constructor<?> applicationEventClassConstructor;
 
+	@Nullable
 	private ApplicationEventPublisher applicationEventPublisher;
 
 
@@ -64,15 +68,14 @@ public class EventPublicationInterceptor
 	 */
 	public void setApplicationEventClass(Class<?> applicationEventClass) {
 		if (ApplicationEvent.class == applicationEventClass ||
-			!ApplicationEvent.class.isAssignableFrom(applicationEventClass)) {
-			throw new IllegalArgumentException("applicationEventClass needs to extend ApplicationEvent");
+				!ApplicationEvent.class.isAssignableFrom(applicationEventClass)) {
+			throw new IllegalArgumentException("'applicationEventClass' needs to extend ApplicationEvent");
 		}
 		try {
-			this.applicationEventClassConstructor =
-					applicationEventClass.getConstructor(new Class<?>[] {Object.class});
+			this.applicationEventClassConstructor = applicationEventClass.getConstructor(Object.class);
 		}
 		catch (NoSuchMethodException ex) {
-			throw new IllegalArgumentException("applicationEventClass [" +
+			throw new IllegalArgumentException("ApplicationEvent class [" +
 					applicationEventClass.getName() + "] does not have the required Object constructor: " + ex);
 		}
 	}
@@ -85,7 +88,7 @@ public class EventPublicationInterceptor
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		if (this.applicationEventClassConstructor == null) {
-			throw new IllegalArgumentException("applicationEventClass is required");
+			throw new IllegalArgumentException("Property 'applicationEventClass' is required");
 		}
 	}
 
@@ -94,8 +97,11 @@ public class EventPublicationInterceptor
 	public Object invoke(MethodInvocation invocation) throws Throwable {
 		Object retVal = invocation.proceed();
 
+		Assert.state(this.applicationEventClassConstructor != null, "No ApplicationEvent class set");
 		ApplicationEvent event = (ApplicationEvent)
-				this.applicationEventClassConstructor.newInstance(new Object[] {invocation.getThis()});
+				this.applicationEventClassConstructor.newInstance(invocation.getThis());
+
+		Assert.state(this.applicationEventPublisher != null, "No ApplicationEventPublisher available");
 		this.applicationEventPublisher.publishEvent(event);
 
 		return retVal;

spring-context/src/main/java/org/springframework/context/event/GenericApplicationListenerAdapter.java

@@ -37,6 +37,7 @@ public class GenericApplicationListenerAdapter implements GenericApplicationList
 
 	private final ApplicationListener<ApplicationEvent> delegate;
 
+	@Nullable
 	private final ResolvableType declaredEventType;
 
 

spring-context/src/main/java/org/springframework/context/event/SimpleApplicationEventMulticaster.java

@@ -48,8 +48,10 @@ import org.springframework.util.ErrorHandler;
  */
 public class SimpleApplicationEventMulticaster extends AbstractApplicationEventMulticaster {
 
+	@Nullable
 	private Executor taskExecutor;
 
+	@Nullable
 	private ErrorHandler errorHandler;
 
 

spring-context/src/main/java/org/springframework/context/event/SourceFilteringListener.java

@@ -38,6 +38,7 @@ public class SourceFilteringListener implements GenericApplicationListener, Smar
 
 	private final Object source;
 
+	@Nullable
 	private GenericApplicationListener delegate;
 
 

spring-context/src/main/java/org/springframework/context/expression/AnnotatedElementKey.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -18,6 +18,7 @@ package org.springframework.context.expression;
 
 import java.lang.reflect.AnnotatedElement;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -34,6 +35,7 @@ public final class AnnotatedElementKey implements Comparable<AnnotatedElementKey
 
 	private final AnnotatedElement element;
 
+	@Nullable
 	private final Class<?> targetClass;
 
 
@@ -41,7 +43,7 @@ public final class AnnotatedElementKey implements Comparable<AnnotatedElementKey
 	 * Create a new instance with the specified {@link AnnotatedElement} and
 	 * optional target {@link Class}.
 	 */
-	public AnnotatedElementKey(AnnotatedElement element, Class<?> targetClass) {
+	public AnnotatedElementKey(AnnotatedElement element, @Nullable Class<?> targetClass) {
 		Assert.notNull(element, "AnnotatedElement must not be null");
 		this.element = element;
 		this.targetClass = targetClass;
@@ -75,6 +77,9 @@ public final class AnnotatedElementKey implements Comparable<AnnotatedElementKey
 	public int compareTo(AnnotatedElementKey other) {
 		int result = this.element.toString().compareTo(other.element.toString());
 		if (result == 0 && this.targetClass != null) {
+			if (other.targetClass == null) {
+				return 1;
+			}
 			result = this.targetClass.getName().compareTo(other.targetClass.getName());
 		}
 		return result;

spring-context/src/main/java/org/springframework/context/expression/CachedExpressionEvaluator.java

@@ -135,7 +135,7 @@ public abstract class CachedExpressionEvaluator {
 		@Override
 		public int compareTo(ExpressionKey other) {
 			int result = this.element.toString().compareTo(other.element.toString());
-			if (result == 0 && this.expression != null) {
+			if (result == 0) {
 				result = this.expression.compareTo(other.expression);
 			}
 			return result;

spring-context/src/main/java/org/springframework/context/expression/StandardBeanExpressionResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -95,7 +95,7 @@ public class StandardBeanExpressionResolver implements BeanExpressionResolver {
 	 * using it as the basis for expression compilation.
 	 * @param beanClassLoader the factory's bean class loader
 	 */
-	public StandardBeanExpressionResolver(ClassLoader beanClassLoader) {
+	public StandardBeanExpressionResolver(@Nullable ClassLoader beanClassLoader) {
 		this.expressionParser = new SpelExpressionParser(new SpelParserConfiguration(null, beanClassLoader));
 	}
 

spring-context/src/main/java/org/springframework/context/i18n/LocaleContextHolder.java

@@ -51,9 +51,11 @@ public abstract class LocaleContextHolder {
 			new NamedInheritableThreadLocal<>("LocaleContext");
 
 	// Shared default locale at the framework level
+	@Nullable
 	private static Locale defaultLocale;
 
 	// Shared default time zone at the framework level
+	@Nullable
 	private static TimeZone defaultTimeZone;
 
 

spring-context/src/main/java/org/springframework/context/i18n/SimpleLocaleContext.java

@@ -32,6 +32,7 @@ import org.springframework.lang.Nullable;
  */
 public class SimpleLocaleContext implements LocaleContext {
 
+	@Nullable
 	private final Locale locale;
 
 
@@ -45,6 +46,7 @@ public class SimpleLocaleContext implements LocaleContext {
 	}
 
 	@Override
+	@Nullable
 	public Locale getLocale() {
 		return this.locale;
 	}

spring-context/src/main/java/org/springframework/context/i18n/SimpleTimeZoneAwareLocaleContext.java

@@ -36,6 +36,7 @@ import org.springframework.lang.Nullable;
  */
 public class SimpleTimeZoneAwareLocaleContext extends SimpleLocaleContext implements TimeZoneAwareLocaleContext {
 
+	@Nullable
 	private final TimeZone timeZone;
 
 
@@ -53,6 +54,7 @@ public class SimpleTimeZoneAwareLocaleContext extends SimpleLocaleContext implem
 
 
 	@Override
+	@Nullable
 	public TimeZone getTimeZone() {
 		return this.timeZone;
 	}

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -167,9 +167,11 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	private String displayName = ObjectUtils.identityToString(this);
 
 	/** Parent context */
+	@Nullable
 	private ApplicationContext parent;
 
 	/** Environment used by this context */
+	@Nullable
 	private ConfigurableEnvironment environment;
 
 	/** BeanFactoryPostProcessors to apply on refresh */
@@ -188,24 +190,29 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	private final Object startupShutdownMonitor = new Object();
 
 	/** Reference to the JVM shutdown hook, if registered */
+	@Nullable
 	private Thread shutdownHook;
 
 	/** ResourcePatternResolver used by this context */
 	private ResourcePatternResolver resourcePatternResolver;
 
 	/** LifecycleProcessor for managing the lifecycle of beans within this context */
+	@Nullable
 	private LifecycleProcessor lifecycleProcessor;
 
 	/** MessageSource we delegate our implementation of this interface to */
+	@Nullable
 	private MessageSource messageSource;
 
 	/** Helper class used in event publishing */
+	@Nullable
 	private ApplicationEventMulticaster applicationEventMulticaster;
 
 	/** Statically specified listeners */
 	private final Set<ApplicationListener<?>> applicationListeners = new LinkedHashSet<>();
 
 	/** ApplicationEvents published early */
+	@Nullable
 	private Set<ApplicationEvent> earlyApplicationEvents;
 
 
@@ -275,6 +282,7 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	 * (that is, this context is the root of the context hierarchy).
 	 */
 	@Override
+	@Nullable
 	public ApplicationContext getParent() {
 		return this.parent;
 	}

spring-context/src/main/java/org/springframework/context/support/AbstractMessageSource.java

@@ -64,8 +64,10 @@ import org.springframework.util.ObjectUtils;
  */
 public abstract class AbstractMessageSource extends MessageSourceSupport implements HierarchicalMessageSource {
 
+	@Nullable
 	private MessageSource parentMessageSource;
 
+	@Nullable
 	private Properties commonMessages;
 
 	private boolean useCodeAsDefaultMessage = false;
@@ -77,6 +79,7 @@ public abstract class AbstractMessageSource extends MessageSourceSupport impleme
 	}
 
 	@Override
+	@Nullable
 	public MessageSource getParentMessageSource() {
 		return this.parentMessageSource;
 	}

spring-context/src/main/java/org/springframework/context/support/AbstractRefreshableApplicationContext.java

@@ -64,11 +64,14 @@ import org.springframework.lang.Nullable;
  */
 public abstract class AbstractRefreshableApplicationContext extends AbstractApplicationContext {
 
+	@Nullable
 	private Boolean allowBeanDefinitionOverriding;
 
+	@Nullable
 	private Boolean allowCircularReferences;
 
 	/** Bean factory for this context */
+	@Nullable
 	private DefaultListableBeanFactory beanFactory;
 
 	/** Synchronization monitor for the internal BeanFactory */
@@ -149,8 +152,10 @@ public abstract class AbstractRefreshableApplicationContext extends AbstractAppl
 	@Override
 	protected final void closeBeanFactory() {
 		synchronized (this.beanFactoryMonitor) {
-			this.beanFactory.setSerializationId(null);
-			this.beanFactory = null;
+			if (this.beanFactory != null) {
+				this.beanFactory.setSerializationId(null);
+				this.beanFactory = null;
+			}
 		}
 	}
 

spring-context/src/main/java/org/springframework/context/support/AbstractRefreshableConfigApplicationContext.java

@@ -39,6 +39,7 @@ import org.springframework.util.StringUtils;
 public abstract class AbstractRefreshableConfigApplicationContext extends AbstractRefreshableApplicationContext
 		implements BeanNameAware, InitializingBean {
 
+	@Nullable
 	private String[] configLocations;
 
 	private boolean setIdCalled = false;

spring-context/src/main/java/org/springframework/context/support/ApplicationListenerDetector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -27,6 +27,7 @@ import org.springframework.beans.factory.support.MergedBeanDefinitionPostProcess
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.event.ApplicationEventMulticaster;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -46,6 +47,7 @@ class ApplicationListenerDetector implements DestructionAwareBeanPostProcessor,
 
 	private static final Log logger = LogFactory.getLog(ApplicationListenerDetector.class);
 
+	@Nullable
 	private transient final AbstractApplicationContext applicationContext;
 
 	private transient final Map<String, Boolean> singletonNames = new ConcurrentHashMap<>(256);

spring-context/src/main/java/org/springframework/context/support/ApplicationObjectSupport.java

@@ -52,9 +52,11 @@ public abstract class ApplicationObjectSupport implements ApplicationContextAwar
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	/** ApplicationContext this object runs in */
+	@Nullable
 	private ApplicationContext applicationContext;
 
 	/** MessageSourceAccessor for easy message access */
+	@Nullable
 	private MessageSourceAccessor messageSourceAccessor;
 
 

spring-context/src/main/java/org/springframework/context/support/ContextTypeMatchClassLoader.java

@@ -23,6 +23,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import org.springframework.core.DecoratingClassLoader;
 import org.springframework.core.OverridingClassLoader;
 import org.springframework.core.SmartClassLoader;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -59,7 +60,7 @@ class ContextTypeMatchClassLoader extends DecoratingClassLoader implements Smart
 	private final Map<String, byte[]> bytesCache = new ConcurrentHashMap<>(256);
 
 
-	public ContextTypeMatchClassLoader(ClassLoader parent) {
+	public ContextTypeMatchClassLoader(@Nullable ClassLoader parent) {
 		super(parent);
 	}
 

spring-context/src/main/java/org/springframework/context/support/DefaultMessageSourceResolvable.java

@@ -35,10 +35,13 @@ import org.springframework.util.StringUtils;
 @SuppressWarnings("serial")
 public class DefaultMessageSourceResolvable implements MessageSourceResolvable, Serializable {
 
+	@Nullable
 	private final String[] codes;
 
+	@Nullable
 	private final Object[] arguments;
 
+	@Nullable
 	private final String defaultMessage;
 
 
@@ -109,16 +112,19 @@ public class DefaultMessageSourceResolvable implements MessageSourceResolvable,
 	}
 
 	@Override
+	@Nullable
 	public String[] getCodes() {
 		return this.codes;
 	}
 
 	@Override
+	@Nullable
 	public Object[] getArguments() {
 		return this.arguments;
 	}
 
 	@Override
+	@Nullable
 	public String getDefaultMessage() {
 		return this.defaultMessage;
 	}

spring-context/src/main/java/org/springframework/context/support/DelegatingMessageSource.java

@@ -37,6 +37,7 @@ import org.springframework.lang.Nullable;
  */
 public class DelegatingMessageSource extends MessageSourceSupport implements HierarchicalMessageSource {
 
+	@Nullable
 	private MessageSource parentMessageSource;
 
 
@@ -46,6 +47,7 @@ public class DelegatingMessageSource extends MessageSourceSupport implements Hie
 	}
 
 	@Override
+	@Nullable
 	public MessageSource getParentMessageSource() {
 		return this.parentMessageSource;
 	}

spring-context/src/main/java/org/springframework/context/support/EmbeddedValueResolutionSupport.java

@@ -29,6 +29,7 @@ import org.springframework.util.StringValueResolver;
  */
 public class EmbeddedValueResolutionSupport implements EmbeddedValueResolverAware {
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
 

spring-context/src/main/java/org/springframework/context/support/GenericApplicationContext.java

@@ -93,6 +93,7 @@ public class GenericApplicationContext extends AbstractApplicationContext implem
 
 	private final DefaultListableBeanFactory beanFactory;
 
+	@Nullable
 	private ResourceLoader resourceLoader;
 
 	private boolean customClassLoader = false;

spring-context/src/main/java/org/springframework/context/support/LiveBeansView.java

@@ -56,9 +56,9 @@ public class LiveBeansView implements LiveBeansViewMBean, ApplicationContextAwar
 
 	public static final String MBEAN_APPLICATION_KEY = "application";
 
-	private static final Set<ConfigurableApplicationContext> applicationContexts =
-			new LinkedHashSet<>();
+	private static final Set<ConfigurableApplicationContext> applicationContexts = new LinkedHashSet<>();
 
+	@Nullable
 	private static String applicationName;
 
 
@@ -103,6 +103,7 @@ public class LiveBeansView implements LiveBeansViewMBean, ApplicationContextAwar
 	}
 
 
+	@Nullable
 	private ConfigurableApplicationContext applicationContext;
 
 

spring-context/src/main/java/org/springframework/context/support/MessageSourceAccessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -39,8 +39,10 @@ public class MessageSourceAccessor {
 
 	private final MessageSource messageSource;
 
+	@Nullable
 	private final Locale defaultLocale;
 
+
 	/**
 	 * Create a new MessageSourceAccessor, using LocaleContextHolder's locale
 	 * as default locale.
@@ -62,6 +64,7 @@ public class MessageSourceAccessor {
 		this.defaultLocale = defaultLocale;
 	}
 
+
 	/**
 	 * Return the default locale to use if no explicit locale has been given.
 	 * <p>The default implementation returns the default locale passed into the

spring-context/src/main/java/org/springframework/context/support/PropertySourcesPlaceholderConfigurer.java

@@ -31,6 +31,7 @@ import org.springframework.core.env.PropertiesPropertySource;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.PropertySources;
 import org.springframework.core.env.PropertySourcesPropertyResolver;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringValueResolver;
 
@@ -75,10 +76,13 @@ public class PropertySourcesPlaceholderConfigurer extends PlaceholderConfigurerS
 	public static final String ENVIRONMENT_PROPERTIES_PROPERTY_SOURCE_NAME = "environmentProperties";
 
 
+	@Nullable
 	private MutablePropertySources propertySources;
 
+	@Nullable
 	private PropertySources appliedPropertySources;
 
+	@Nullable
 	private Environment environment;
 
 

spring-context/src/main/java/org/springframework/context/support/ReloadableResourceBundleMessageSource.java

@@ -92,6 +92,7 @@ public class ReloadableResourceBundleMessageSource extends AbstractResourceBased
 	private static final String XML_SUFFIX = ".xml";
 
 
+	@Nullable
 	private Properties fileEncodings;
 
 	private boolean concurrentRefresh = true;
@@ -549,6 +550,7 @@ public class ReloadableResourceBundleMessageSource extends AbstractResourceBased
 	 */
 	protected class PropertiesHolder {
 
+		@Nullable
 		private final Properties properties;
 
 		private final long fileTimestamp;

spring-context/src/main/java/org/springframework/context/support/ResourceBundleMessageSource.java

@@ -36,6 +36,7 @@ import java.util.Set;
 
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -66,8 +67,10 @@ import org.springframework.util.ClassUtils;
  */
 public class ResourceBundleMessageSource extends AbstractResourceBasedMessageSource implements BeanClassLoaderAware {
 
+	@Nullable
 	private ClassLoader bundleClassLoader;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	/**
@@ -77,8 +80,7 @@ public class ResourceBundleMessageSource extends AbstractResourceBasedMessageSou
 	 * This allows for very efficient hash lookups, significantly faster
 	 * than the ResourceBundle class's own cache.
 	 */
-	private final Map<String, Map<Locale, ResourceBundle>> cachedResourceBundles =
-			new HashMap<>();
+	private final Map<String, Map<Locale, ResourceBundle>> cachedResourceBundles = new HashMap<>();
 
 	/**
 	 * Cache to hold already generated MessageFormats.
@@ -88,8 +90,7 @@ public class ResourceBundleMessageSource extends AbstractResourceBasedMessageSou
 	 * very efficient hash lookups without concatenated keys.
 	 * @see #getMessageFormat
 	 */
-	private final Map<ResourceBundle, Map<String, Map<Locale, MessageFormat>>> cachedBundleMessageFormats =
-			new HashMap<>();
+	private final Map<ResourceBundle, Map<String, Map<Locale, MessageFormat>>> cachedBundleMessageFormats = new HashMap<>();
 
 
 	/**
@@ -109,6 +110,7 @@ public class ResourceBundleMessageSource extends AbstractResourceBasedMessageSou
 	 * <p>Default is the containing BeanFactory's bean ClassLoader.
 	 * @see #setBundleClassLoader
 	 */
+	@Nullable
 	protected ClassLoader getBundleClassLoader() {
 		return (this.bundleClassLoader != null ? this.bundleClassLoader : this.beanClassLoader);
 	}
@@ -214,7 +216,9 @@ public class ResourceBundleMessageSource extends AbstractResourceBasedMessageSou
 	 * @see #getBundleClassLoader()
 	 */
 	protected ResourceBundle doGetBundle(String basename, Locale locale) throws MissingResourceException {
-		return ResourceBundle.getBundle(basename, locale, getBundleClassLoader(), new MessageSourceControl());
+		ClassLoader classLoader = getBundleClassLoader();
+		Assert.state(classLoader != null, "No bundle ClassLoader set");
+		return ResourceBundle.getBundle(basename, locale, classLoader, new MessageSourceControl());
 	}
 
 	/**

spring-context/src/main/java/org/springframework/context/weaving/AspectJWeavingEnabler.java

@@ -78,7 +78,9 @@ public class AspectJWeavingEnabler
 	 * @param weaverToUse the LoadTimeWeaver to apply to (or {@code null} for a default weaver)
 	 * @param beanClassLoader the class loader to create a default weaver for (if necessary)
 	 */
-	public static void enableAspectJWeaving(@Nullable LoadTimeWeaver weaverToUse, ClassLoader beanClassLoader) {
+	public static void enableAspectJWeaving(
+			@Nullable LoadTimeWeaver weaverToUse, @Nullable ClassLoader beanClassLoader) {
+
 		if (weaverToUse == null) {
 			if (InstrumentationLoadTimeWeaver.isInstrumentationAvailable()) {
 				weaverToUse = new InstrumentationLoadTimeWeaver(beanClassLoader);

spring-context/src/main/java/org/springframework/context/weaving/DefaultContextLoadTimeWeaver.java

@@ -33,6 +33,7 @@ import org.springframework.instrument.classloading.tomcat.TomcatLoadTimeWeaver;
 import org.springframework.instrument.classloading.weblogic.WebLogicLoadTimeWeaver;
 import org.springframework.instrument.classloading.websphere.WebSphereLoadTimeWeaver;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Default {@link LoadTimeWeaver} bean for use in an application context,
@@ -58,6 +59,7 @@ public class DefaultContextLoadTimeWeaver implements LoadTimeWeaver, BeanClassLo
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private LoadTimeWeaver loadTimeWeaver;
 
 
@@ -68,6 +70,7 @@ public class DefaultContextLoadTimeWeaver implements LoadTimeWeaver, BeanClassLo
 		setBeanClassLoader(beanClassLoader);
 	}
 
+
 	@Override
 	public void setBeanClassLoader(ClassLoader classLoader) {
 		LoadTimeWeaver serverSpecificLoadTimeWeaver = createServerSpecificLoadTimeWeaver(classLoader);
@@ -148,16 +151,19 @@ public class DefaultContextLoadTimeWeaver implements LoadTimeWeaver, BeanClassLo
 
 	@Override
 	public void addTransformer(ClassFileTransformer transformer) {
+		Assert.state(this.loadTimeWeaver != null, "Not initialized");
 		this.loadTimeWeaver.addTransformer(transformer);
 	}
 
 	@Override
 	public ClassLoader getInstrumentableClassLoader() {
+		Assert.state(this.loadTimeWeaver != null, "Not initialized");
 		return this.loadTimeWeaver.getInstrumentableClassLoader();
 	}
 
 	@Override
 	public ClassLoader getThrowawayClassLoader() {
+		Assert.state(this.loadTimeWeaver != null, "Not initialized");
 		return this.loadTimeWeaver.getThrowawayClassLoader();
 	}
 

spring-context/src/main/java/org/springframework/context/weaving/LoadTimeWeaverAwareProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -43,8 +43,10 @@ import org.springframework.util.Assert;
  */
 public class LoadTimeWeaverAwareProcessor implements BeanPostProcessor, BeanFactoryAware {
 
+	@Nullable
 	private LoadTimeWeaver loadTimeWeaver;
 
+	@Nullable
 	private BeanFactory beanFactory;
 
 

spring-context/src/main/java/org/springframework/ejb/access/AbstractSlsbInvokerInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -51,11 +51,13 @@ public abstract class AbstractSlsbInvokerInterceptor extends JndiObjectLocator
 	 * The EJB's home object, potentially cached.
 	 * The type must be Object as it could be either EJBHome or EJBLocalHome.
 	 */
+	@Nullable
 	private Object cachedHome;
 
 	/**
 	 * The no-arg create() method required on EJB homes, potentially cached.
 	 */
+	@Nullable
 	private Method createMethod;
 
 	private final Object homeMonitor = new Object();

spring-context/src/main/java/org/springframework/ejb/access/LocalStatelessSessionProxyFactoryBean.java

@@ -21,6 +21,7 @@ import javax.naming.NamingException;
 import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -52,11 +53,14 @@ public class LocalStatelessSessionProxyFactoryBean extends LocalSlsbInvokerInter
 		implements FactoryBean<Object>, BeanClassLoaderAware {
 
 	/** The business interface of the EJB we're proxying */
+	@Nullable
 	private Class<?> businessInterface;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	/** EJBLocalObject */
+	@Nullable
 	private Object proxy;
 
 
@@ -73,6 +77,7 @@ public class LocalStatelessSessionProxyFactoryBean extends LocalSlsbInvokerInter
 	/**
 	 * Return the business interface of the EJB we're proxying.
 	 */
+	@Nullable
 	public Class<?> getBusinessInterface() {
 		return this.businessInterface;
 	}

spring-context/src/main/java/org/springframework/ejb/access/SimpleRemoteSlsbInvokerInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.naming.NamingException;
 import org.aopalliance.intercept.MethodInvocation;
 
 import org.springframework.beans.factory.DisposableBean;
+import org.springframework.lang.Nullable;
 import org.springframework.remoting.RemoteLookupFailureException;
 import org.springframework.remoting.rmi.RmiClientInterceptorUtils;
 
@@ -66,6 +67,7 @@ public class SimpleRemoteSlsbInvokerInterceptor extends AbstractRemoteSlsbInvoke
 
 	private boolean cacheSessionBean = false;
 
+	@Nullable
 	private Object beanInstance;
 
 	private final Object beanInstanceMonitor = new Object();

spring-context/src/main/java/org/springframework/ejb/access/SimpleRemoteStatelessSessionProxyFactoryBean.java

@@ -21,6 +21,7 @@ import javax.naming.NamingException;
 import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -62,11 +63,14 @@ public class SimpleRemoteStatelessSessionProxyFactoryBean extends SimpleRemoteSl
 	implements FactoryBean<Object>, BeanClassLoaderAware {
 
 	/** The business interface of the EJB we're proxying */
+	@Nullable
 	private Class<?> businessInterface;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	/** EJBObject */
+	@Nullable
 	private Object proxy;
 
 
@@ -87,6 +91,7 @@ public class SimpleRemoteStatelessSessionProxyFactoryBean extends SimpleRemoteSl
 	/**
 	 * Return the business interface of the EJB we're proxying.
 	 */
+	@Nullable
 	public Class<?> getBusinessInterface() {
 		return this.businessInterface;
 	}

spring-context/src/main/java/org/springframework/format/datetime/DateFormatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -28,6 +28,7 @@ import java.util.TimeZone;
 
 import org.springframework.format.Formatter;
 import org.springframework.format.annotation.DateTimeFormat.ISO;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -55,14 +56,18 @@ public class DateFormatter implements Formatter<Date> {
 	}
 
 
+	@Nullable
 	private String pattern;
 
 	private int style = DateFormat.DEFAULT;
 
+	@Nullable
 	private String stylePattern;
 
+	@Nullable
 	private ISO iso;
 
+	@Nullable
 	private TimeZone timeZone;
 
 	private boolean lenient = false;

spring-context/src/main/java/org/springframework/format/datetime/DateFormatterRegistrar.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -23,6 +23,7 @@ import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.ConverterRegistry;
 import org.springframework.format.FormatterRegistrar;
 import org.springframework.format.FormatterRegistry;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -42,6 +43,7 @@ import org.springframework.util.Assert;
  */
 public class DateFormatterRegistrar implements FormatterRegistrar {
 
+	@Nullable
 	private DateFormatter dateFormatter;
 
 

spring-context/src/main/java/org/springframework/format/datetime/joda/DateTimeFormatterFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -24,6 +24,7 @@ import org.joda.time.format.DateTimeFormatter;
 import org.joda.time.format.ISODateTimeFormat;
 
 import org.springframework.format.annotation.DateTimeFormat.ISO;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -44,12 +45,16 @@ import org.springframework.util.StringUtils;
  */
 public class DateTimeFormatterFactory {
 
+	@Nullable
 	private String pattern;
 
+	@Nullable
 	private ISO iso;
 
+	@Nullable
 	private String style;
 
+	@Nullable
 	private TimeZone timeZone;
 
 

spring-context/src/main/java/org/springframework/format/datetime/joda/JodaTimeContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -39,8 +39,10 @@ import org.springframework.lang.Nullable;
  */
 public class JodaTimeContext {
 
+	@Nullable
 	private Chronology chronology;
 
+	@Nullable
 	private DateTimeZone timeZone;
 
 

spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -37,8 +37,10 @@ import org.springframework.lang.Nullable;
  */
 public class DateTimeContext {
 
+	@Nullable
 	private Chronology chronology;
 
+	@Nullable
 	private ZoneId timeZone;
 
 

spring-context/src/main/java/org/springframework/format/datetime/standard/DateTimeFormatterFactory.java

@@ -46,14 +46,19 @@ import org.springframework.util.StringUtils;
  */
 public class DateTimeFormatterFactory {
 
+	@Nullable
 	private String pattern;
 
+	@Nullable
 	private ISO iso;
 
+	@Nullable
 	private FormatStyle dateStyle;
 
+	@Nullable
 	private FormatStyle timeStyle;
 
+	@Nullable
 	private TimeZone timeZone;
 
 

spring-context/src/main/java/org/springframework/format/number/CurrencyStyleFormatter.java

@@ -24,6 +24,8 @@ import java.text.ParseException;
 import java.util.Currency;
 import java.util.Locale;
 
+import org.springframework.lang.Nullable;
+
 /**
  * A BigDecimal formatter for number values in currency style.
  *
@@ -41,10 +43,13 @@ public class CurrencyStyleFormatter extends AbstractNumberFormatter {
 
 	private int fractionDigits = 2;
 
+	@Nullable
 	private RoundingMode roundingMode;
 
+	@Nullable
 	private Currency currency;
 
+	@Nullable
 	private String pattern;
 
 

spring-context/src/main/java/org/springframework/format/number/NumberStyleFormatter.java

@@ -20,6 +20,8 @@ import java.text.DecimalFormat;
 import java.text.NumberFormat;
 import java.util.Locale;
 
+import org.springframework.lang.Nullable;
+
 /**
  * A general-purpose number formatter using NumberFormat's number style.
  *
@@ -36,6 +38,7 @@ import java.util.Locale;
  */
 public class NumberStyleFormatter extends AbstractNumberFormatter {
 
+	@Nullable
 	private String pattern;
 
 

spring-context/src/main/java/org/springframework/format/number/money/MonetaryAmountFormatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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 javax.money.format.MonetaryAmountFormat;
 import javax.money.format.MonetaryFormats;
 
 import org.springframework.format.Formatter;
+import org.springframework.lang.Nullable;
 
 /**
  * Formatter for JSR-354 {@link javax.money.MonetaryAmount} values,
@@ -34,6 +35,7 @@ import org.springframework.format.Formatter;
  */
 public class MonetaryAmountFormatter implements Formatter<MonetaryAmount> {
 
+	@Nullable
 	private String formatName;
 
 

spring-context/src/main/java/org/springframework/format/support/FormattingConversionService.java

@@ -51,6 +51,7 @@ import org.springframework.util.StringValueResolver;
 public class FormattingConversionService extends GenericConversionService
 		implements FormatterRegistry, EmbeddedValueResolverAware {
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
 	private final Map<AnnotationConverterKey, GenericConverter> cachedPrinters = new ConcurrentHashMap<>(64);

spring-context/src/main/java/org/springframework/format/support/FormattingConversionServiceFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -28,6 +28,7 @@ import org.springframework.format.FormatterRegistrar;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.format.Parser;
 import org.springframework.format.Printer;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringValueResolver;
 
 /**
@@ -63,16 +64,21 @@ import org.springframework.util.StringValueResolver;
 public class FormattingConversionServiceFactoryBean
 		implements FactoryBean<FormattingConversionService>, EmbeddedValueResolverAware, InitializingBean {
 
+	@Nullable
 	private Set<?> converters;
 
+	@Nullable
 	private Set<?> formatters;
 
+	@Nullable
 	private Set<FormatterRegistrar> formatterRegistrars;
 
 	private boolean registerDefaultFormatters = true;
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
+	@Nullable
 	private FormattingConversionService conversionService;
 
 
@@ -134,17 +140,17 @@ public class FormattingConversionServiceFactoryBean
 	public void afterPropertiesSet() {
 		this.conversionService = new DefaultFormattingConversionService(this.embeddedValueResolver, this.registerDefaultFormatters);
 		ConversionServiceFactory.registerConverters(this.converters, this.conversionService);
-		registerFormatters();
+		registerFormatters(this.conversionService);
 	}
 
-	private void registerFormatters() {
+	private void registerFormatters(FormattingConversionService conversionService) {
 		if (this.formatters != null) {
 			for (Object formatter : this.formatters) {
 				if (formatter instanceof Formatter<?>) {
-					this.conversionService.addFormatter((Formatter<?>) formatter);
+					conversionService.addFormatter((Formatter<?>) formatter);
 				}
 				else if (formatter instanceof AnnotationFormatterFactory<?>) {
-					this.conversionService.addFormatterForFieldAnnotation((AnnotationFormatterFactory<?>) formatter);
+					conversionService.addFormatterForFieldAnnotation((AnnotationFormatterFactory<?>) formatter);
 				}
 				else {
 					throw new IllegalArgumentException(
@@ -154,7 +160,7 @@ public class FormattingConversionServiceFactoryBean
 		}
 		if (this.formatterRegistrars != null) {
 			for (FormatterRegistrar registrar : this.formatterRegistrars) {
-				registrar.registerFormatters(this.conversionService);
+				registrar.registerFormatters(conversionService);
 			}
 		}
 	}

spring-context/src/main/java/org/springframework/instrument/classloading/InstrumentationLoadTimeWeaver.java

@@ -54,8 +54,10 @@ public class InstrumentationLoadTimeWeaver implements LoadTimeWeaver {
 			InstrumentationLoadTimeWeaver.class.getClassLoader());
 
 
+	@Nullable
 	private final ClassLoader classLoader;
 
+	@Nullable
 	private final Instrumentation instrumentation;
 
 	private final List<ClassFileTransformer> transformers = new ArrayList<>(4);
@@ -115,7 +117,7 @@ public class InstrumentationLoadTimeWeaver implements LoadTimeWeaver {
 	 */
 	public void removeTransformers() {
 		synchronized (this.transformers) {
-			if (!this.transformers.isEmpty()) {
+			if (this.instrumentation != null && !this.transformers.isEmpty()) {
 				for (int i = this.transformers.size() - 1; i >= 0; i--) {
 					this.instrumentation.removeTransformer(this.transformers.get(i));
 				}
@@ -167,9 +169,12 @@ public class InstrumentationLoadTimeWeaver implements LoadTimeWeaver {
 
 		private final ClassFileTransformer targetTransformer;
 
+		@Nullable
 		private final ClassLoader targetClassLoader;
 
-		public FilteringClassFileTransformer(ClassFileTransformer targetTransformer, ClassLoader targetClassLoader) {
+		public FilteringClassFileTransformer(
+				ClassFileTransformer targetTransformer, @Nullable ClassLoader targetClassLoader) {
+
 			this.targetTransformer = targetTransformer;
 			this.targetClassLoader = targetClassLoader;
 		}
@@ -179,7 +184,7 @@ public class InstrumentationLoadTimeWeaver implements LoadTimeWeaver {
 		public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
 				ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
 
-			if (!this.targetClassLoader.equals(loader)) {
+			if (this.targetClassLoader != loader) {
 				return null;
 			}
 			return this.targetTransformer.transform(

spring-context/src/main/java/org/springframework/instrument/classloading/ReflectiveLoadTimeWeaver.java

@@ -76,6 +76,7 @@ public class ReflectiveLoadTimeWeaver implements LoadTimeWeaver {
 
 	private final Method addTransformerMethod;
 
+	@Nullable
 	private final Method getThrowawayClassLoaderMethod;
 
 
@@ -97,22 +98,26 @@ public class ReflectiveLoadTimeWeaver implements LoadTimeWeaver {
 	public ReflectiveLoadTimeWeaver(@Nullable ClassLoader classLoader) {
 		Assert.notNull(classLoader, "ClassLoader must not be null");
 		this.classLoader = classLoader;
-		this.addTransformerMethod = ClassUtils.getMethodIfAvailable(
+
+		Method addTransformerMethod = ClassUtils.getMethodIfAvailable(
 				this.classLoader.getClass(), ADD_TRANSFORMER_METHOD_NAME, ClassFileTransformer.class);
-		if (this.addTransformerMethod == null) {
+		if (addTransformerMethod == null) {
 			throw new IllegalStateException(
 					"ClassLoader [" + classLoader.getClass().getName() + "] does NOT provide an " +
 					"'addTransformer(ClassFileTransformer)' method.");
 		}
-		this.getThrowawayClassLoaderMethod = ClassUtils.getMethodIfAvailable(
+		this.addTransformerMethod = addTransformerMethod;
+
+		Method getThrowawayClassLoaderMethod = ClassUtils.getMethodIfAvailable(
 				this.classLoader.getClass(), GET_THROWAWAY_CLASS_LOADER_METHOD_NAME);
 		// getThrowawayClassLoader method is optional
-		if (this.getThrowawayClassLoaderMethod == null) {
+		if (getThrowawayClassLoaderMethod == null) {
 			if (logger.isInfoEnabled()) {
 				logger.info("The ClassLoader [" + classLoader.getClass().getName() + "] does NOT provide a " +
 						"'getThrowawayClassLoader()' method; SimpleThrowawayClassLoader will be used instead.");
 			}
 		}
+		this.getThrowawayClassLoaderMethod = getThrowawayClassLoaderMethod;
 	}
 
 

spring-context/src/main/java/org/springframework/instrument/classloading/WeavingTransformer.java

@@ -39,6 +39,7 @@ import org.springframework.util.Assert;
  */
 public class WeavingTransformer {
 
+	@Nullable
 	private final ClassLoader classLoader;
 
 	private final List<ClassFileTransformer> transformers = new ArrayList<>();

spring-context/src/main/java/org/springframework/instrument/classloading/jboss/JBossLoadTimeWeaver.java

@@ -67,6 +67,7 @@ public class JBossLoadTimeWeaver implements LoadTimeWeaver {
 	public JBossLoadTimeWeaver(@Nullable ClassLoader classLoader) {
 		Assert.notNull(classLoader, "ClassLoader must not be null");
 		this.classLoader = classLoader;
+
 		try {
 			Field transformer = ReflectionUtils.findField(classLoader.getClass(), "transformer");
 			if (transformer == null) {
@@ -74,20 +75,23 @@ public class JBossLoadTimeWeaver implements LoadTimeWeaver {
 						classLoader.getClass().getName());
 			}
 			transformer.setAccessible(true);
+
 			this.delegatingTransformer = transformer.get(classLoader);
 			if (!this.delegatingTransformer.getClass().getName().equals(DELEGATING_TRANSFORMER_CLASS_NAME)) {
 				throw new IllegalStateException(
 						"Transformer not of the expected type DelegatingClassFileTransformer: " +
 						this.delegatingTransformer.getClass().getName());
 			}
-			this.addTransformer = ReflectionUtils.findMethod(this.delegatingTransformer.getClass(),
+
+			Method addTransformer = ReflectionUtils.findMethod(this.delegatingTransformer.getClass(),
 					"addTransformer", ClassFileTransformer.class);
-			if (this.addTransformer == null) {
+			if (addTransformer == null) {
 				throw new IllegalArgumentException(
 						"Could not find 'addTransformer' method on JBoss DelegatingClassFileTransformer: " +
 						this.delegatingTransformer.getClass().getName());
 			}
-			this.addTransformer.setAccessible(true);
+			addTransformer.setAccessible(true);
+			this.addTransformer = addTransformer;
 		}
 		catch (Throwable ex) {
 			throw new IllegalStateException("Could not initialize JBoss LoadTimeWeaver", ex);

spring-context/src/main/java/org/springframework/jmx/access/ConnectorDelegate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -40,6 +40,7 @@ class ConnectorDelegate {
 
 	private static final Log logger = LogFactory.getLog(ConnectorDelegate.class);
 
+	@Nullable
 	private JMXConnector connector;
 
 

spring-context/src/main/java/org/springframework/jmx/access/MBeanClientInterceptor.java

@@ -23,6 +23,7 @@ import java.lang.reflect.Method;
 import java.net.MalformedURLException;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import javax.management.Attribute;
@@ -62,6 +63,7 @@ import org.springframework.core.ResolvableType;
 import org.springframework.jmx.support.JmxUtils;
 import org.springframework.jmx.support.ObjectNameManager;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
@@ -93,35 +95,44 @@ public class MBeanClientInterceptor
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private MBeanServerConnection server;
 
+	@Nullable
 	private JMXServiceURL serviceUrl;
 
+	@Nullable
 	private Map<String, ?> environment;
 
+	@Nullable
 	private String agentId;
 
 	private boolean connectOnStartup = true;
 
 	private boolean refreshOnConnectFailure = false;
 
+	@Nullable
 	private ObjectName objectName;
 
 	private boolean useStrictCasing = true;
 
+	@Nullable
 	private Class<?> managementInterface;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	private final ConnectorDelegate connector = new ConnectorDelegate();
 
+	@Nullable
 	private MBeanServerConnection serverToUse;
 
+	@Nullable
 	private MBeanServerInvocationHandler invocationHandler;
 
-	private Map<String, MBeanAttributeInfo> allowedAttributes;
+	private Map<String, MBeanAttributeInfo> allowedAttributes = Collections.emptyMap();
 
-	private Map<MethodCacheKey, MBeanOperationInfo> allowedOperations;
+	private Map<MethodCacheKey, MBeanOperationInfo> allowedOperations = Collections.emptyMap();
 
 	private final Map<Method, String[]> signatureCache = new HashMap<>();
 
@@ -158,6 +169,7 @@ public class MBeanClientInterceptor
 	 * "environment[myKey]". This is particularly useful for
 	 * adding or overriding entries in child bean definitions.
 	 */
+	@Nullable
 	public Map<String, ?> getEnvironment() {
 		return this.environment;
 	}
@@ -231,7 +243,7 @@ public class MBeanClientInterceptor
 	}
 
 	@Override
-	public void setBeanClassLoader(@Nullable ClassLoader beanClassLoader) {
+	public void setBeanClassLoader(ClassLoader beanClassLoader) {
 		this.beanClassLoader = beanClassLoader;
 	}
 
@@ -266,6 +278,7 @@ public class MBeanClientInterceptor
 			}
 			this.invocationHandler = null;
 			if (this.useStrictCasing) {
+				Assert.state(this.objectName != null, "No ObjectName set");
 				// Use the JDK's own MBeanServerInvocationHandler, in particular for native MXBean support.
 				this.invocationHandler = new MBeanServerInvocationHandler(this.serverToUse, this.objectName,
 						(this.managementInterface != null && JMX.isMXBeanInterface(this.managementInterface)));
@@ -273,7 +286,7 @@ public class MBeanClientInterceptor
 			else {
 				// Non-strict casing can only be achieved through custom invocation handling.
 				// Only partial MXBean support available!
-				retrieveMBeanInfo();
+				retrieveMBeanInfo(this.serverToUse);
 			}
 		}
 	}
@@ -282,9 +295,9 @@ public class MBeanClientInterceptor
 	 * This information is used by the proxy when determining whether an invocation matches
 	 * a valid operation or attribute on the management interface of the managed resource.
 	 */
-	private void retrieveMBeanInfo() throws MBeanInfoRetrievalException {
+	private void retrieveMBeanInfo(MBeanServerConnection server) throws MBeanInfoRetrievalException {
 		try {
-			MBeanInfo info = this.serverToUse.getMBeanInfo(this.objectName);
+			MBeanInfo info = server.getMBeanInfo(this.objectName);
 
 			MBeanAttributeInfo[] attributeInfo = info.getAttributes();
 			this.allowedAttributes = new HashMap<>(attributeInfo.length);
@@ -401,7 +414,7 @@ public class MBeanClientInterceptor
 	protected Object doInvoke(MethodInvocation invocation) throws Throwable {
 		Method method = invocation.getMethod();
 		try {
-			Object result = null;
+			Object result;
 			if (this.invocationHandler != null) {
 				result = this.invocationHandler.invoke(invocation.getThis(), method, invocation.getArguments());
 			}
@@ -468,6 +481,8 @@ public class MBeanClientInterceptor
 	private Object invokeAttribute(PropertyDescriptor pd, MethodInvocation invocation)
 			throws JMException, IOException {
 
+		Assert.state(this.serverToUse != null, "No MBeanServerConnection available");
+
 		String attributeName = JmxUtils.getAttributeName(pd, this.useStrictCasing);
 		MBeanAttributeInfo inf = this.allowedAttributes.get(attributeName);
 		// If no attribute is returned, we know that it is not defined in the
@@ -476,6 +491,7 @@ public class MBeanClientInterceptor
 			throw new InvalidInvocationException(
 					"Attribute '" + pd.getName() + "' is not exposed on the management interface");
 		}
+
 		if (invocation.getMethod().equals(pd.getReadMethod())) {
 			if (inf.isReadable()) {
 				return this.serverToUse.getAttribute(this.objectName, attributeName);
@@ -507,13 +523,16 @@ public class MBeanClientInterceptor
 	 * @return the value returned by the method invocation.
 	 */
 	private Object invokeOperation(Method method, Object[] args) throws JMException, IOException {
+		Assert.state(this.serverToUse != null, "No MBeanServerConnection available");
+
 		MethodCacheKey key = new MethodCacheKey(method.getName(), method.getParameterTypes());
 		MBeanOperationInfo info = this.allowedOperations.get(key);
 		if (info == null) {
 			throw new InvalidInvocationException("Operation '" + method.getName() +
 					"' is not exposed on the management interface");
 		}
-		String[] signature = null;
+
+		String[] signature;
 		synchronized (this.signatureCache) {
 			signature = this.signatureCache.get(method);
 			if (signature == null) {
@@ -521,6 +540,7 @@ public class MBeanClientInterceptor
 				this.signatureCache.put(method, signature);
 			}
 		}
+
 		return this.serverToUse.invoke(this.objectName, method.getName(), args, signature);
 	}
 

spring-context/src/main/java/org/springframework/jmx/access/MBeanProxyFactoryBean.java

@@ -21,6 +21,7 @@ import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.jmx.MBeanServerNotFoundException;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -48,10 +49,13 @@ import org.springframework.util.ClassUtils;
 public class MBeanProxyFactoryBean extends MBeanClientInterceptor
 		implements FactoryBean<Object>, BeanClassLoaderAware, InitializingBean {
 
+	@Nullable
 	private Class<?> proxyInterface;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
+	@Nullable
 	private Object mbeanProxy;
 
 

spring-context/src/main/java/org/springframework/jmx/access/NotificationListenerRegistrar.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -32,6 +32,7 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.jmx.JmxException;
 import org.springframework.jmx.MBeanServerNotFoundException;
 import org.springframework.jmx.support.NotificationListenerHolder;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -51,16 +52,21 @@ public class NotificationListenerRegistrar extends NotificationListenerHolder
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	private MBeanServerConnection server;
-
-	private JMXServiceURL serviceUrl;
-
-	private Map<String, ?> environment;
-
-	private String agentId;
-
 	private final ConnectorDelegate connector = new ConnectorDelegate();
 
+	@Nullable
+	private MBeanServerConnection server;
+
+	@Nullable
+	private JMXServiceURL serviceUrl;
+
+	@Nullable
+	private Map<String, ?> environment;
+
+	@Nullable
+	private String agentId;
+
+	@Nullable
 	private ObjectName[] actualObjectNames;
 
 
@@ -87,6 +93,7 @@ public class NotificationListenerRegistrar extends NotificationListenerHolder
 	 * "environment[myKey]". This is particularly useful for
 	 * adding or overriding entries in child bean definitions.
 	 */
+	@Nullable
 	public Map<String, ?> getEnvironment() {
 		return this.environment;
 	}
@@ -133,12 +140,14 @@ public class NotificationListenerRegistrar extends NotificationListenerHolder
 		}
 		try {
 			this.actualObjectNames = getResolvedObjectNames();
-			if (logger.isDebugEnabled()) {
-				logger.debug("Registering NotificationListener for MBeans " + Arrays.asList(this.actualObjectNames));
-			}
-			for (ObjectName actualObjectName : this.actualObjectNames) {
-				this.server.addNotificationListener(
-						actualObjectName, getNotificationListener(), getNotificationFilter(), getHandback());
+			if (this.actualObjectNames != null) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Registering NotificationListener for MBeans " + Arrays.asList(this.actualObjectNames));
+				}
+				for (ObjectName actualObjectName : this.actualObjectNames) {
+					this.server.addNotificationListener(
+							actualObjectName, getNotificationListener(), getNotificationFilter(), getHandback());
+				}
 			}
 		}
 		catch (IOException ex) {
@@ -156,7 +165,7 @@ public class NotificationListenerRegistrar extends NotificationListenerHolder
 	@Override
 	public void destroy() {
 		try {
-			if (this.actualObjectNames != null) {
+			if (this.server != null && this.actualObjectNames != null) {
 				for (ObjectName actualObjectName : this.actualObjectNames) {
 					try {
 						this.server.removeNotificationListener(

spring-context/src/main/java/org/springframework/jmx/export/MBeanExporter.java

@@ -141,9 +141,11 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	private static final Constants constants = new Constants(MBeanExporter.class);
 
 	/** The beans to be exposed as JMX managed resources, with JMX names as keys */
+	@Nullable
 	private Map<String, Object> beans;
 
 	/** The autodetect mode to use for this MBeanExporter */
+	@Nullable
 	private Integer autodetectMode;
 
 	/** Whether to eagerly initialize candidate beans when autodetecting MBeans */
@@ -165,19 +167,22 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	private Set<String> excludedBeans = new HashSet<>();
 
 	/** The MBeanExporterListeners registered with this exporter. */
+	@Nullable
 	private MBeanExporterListener[] listeners;
 
 	/** The NotificationListeners to register for the MBeans registered by this exporter */
+	@Nullable
 	private NotificationListenerBean[] notificationListeners;
 
 	/** Map of actually registered NotificationListeners */
-	private final Map<NotificationListenerBean, ObjectName[]> registeredNotificationListeners =
-			new LinkedHashMap<>();
+	private final Map<NotificationListenerBean, ObjectName[]> registeredNotificationListeners = new LinkedHashMap<>();
 
 	/** Stores the ClassLoader to use for generating lazy-init proxies */
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	/** Stores the BeanFactory for use in autodetection process */
+	@Nullable
 	private ListableBeanFactory beanFactory;
 
 
@@ -534,18 +539,17 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 			if (mode == AUTODETECT_MBEAN || mode == AUTODETECT_ALL) {
 				// Autodetect any beans that are already MBeans.
 				logger.debug("Autodetecting user-defined JMX MBeans");
-				autodetectMBeans();
+				autodetect(this.beans, (beanClass, beanName) -> isMBean(beanClass));
 			}
 			// Allow the assembler a chance to vote for bean inclusion.
 			if ((mode == AUTODETECT_ASSEMBLER || mode == AUTODETECT_ALL) &&
 					this.assembler instanceof AutodetectCapableMBeanInfoAssembler) {
-				autodetectBeans((AutodetectCapableMBeanInfoAssembler) this.assembler);
+				autodetect(this.beans, ((AutodetectCapableMBeanInfoAssembler) this.assembler)::includeBean);
 			}
 		}
 
 		if (!this.beans.isEmpty()) {
-			this.beans.forEach((beanName, instance) ->
-					registerBeanNameOrInstance(instance, beanName));
+			this.beans.forEach((beanName, instance) -> registerBeanNameOrInstance(instance, beanName));
 		}
 	}
 
@@ -699,6 +703,8 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	 * with the {@code MBeanServer}
 	 */
 	private ObjectName registerLazyInit(String beanName, String beanKey) throws JMException {
+		Assert.state(this.beanFactory != null, "No BeanFactory set");
+
 		ProxyFactory proxyFactory = new ProxyFactory();
 		proxyFactory.setProxyTargetClass(true);
 		proxyFactory.setFrozen(true);
@@ -863,26 +869,6 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	// Autodetection process
 	//---------------------------------------------------------------------
 
-	/**
-	 * Invoked when using an {@code AutodetectCapableMBeanInfoAssembler}.
-	 * Gives the assembler the opportunity to add additional beans from the
-	 * {@code BeanFactory} to the list of beans to be exposed via JMX.
-	 * <p>This implementation prevents a bean from being added to the list
-	 * automatically if it has already been added manually, and it prevents
-	 * certain internal classes from being registered automatically.
-	 */
-	private void autodetectBeans(final AutodetectCapableMBeanInfoAssembler assembler) {
-		autodetect((beanClass, beanName) -> assembler.includeBean(beanClass, beanName));
-	}
-
-	/**
-	 * Attempts to detect any beans defined in the {@code ApplicationContext} that are
-	 * valid MBeans and registers them automatically with the {@code MBeanServer}.
-	 */
-	private void autodetectMBeans() {
-		autodetect((beanClass, beanName) -> isMBean(beanClass));
-	}
-
 	/**
 	 * Performs the actual autodetection process, delegating to an
 	 * {@code AutodetectCallback} instance to vote on the inclusion of a
@@ -890,12 +876,14 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	 * @param callback the {@code AutodetectCallback} to use when deciding
 	 * whether to include a bean or not
 	 */
-	private void autodetect(AutodetectCallback callback) {
+	private void autodetect(Map<String, Object> beans, AutodetectCallback callback) {
+		Assert.state(this.beanFactory != null, "No BeanFactory set");
 		Set<String> beanNames = new LinkedHashSet<>(this.beanFactory.getBeanDefinitionCount());
 		beanNames.addAll(Arrays.asList(this.beanFactory.getBeanDefinitionNames()));
 		if (this.beanFactory instanceof ConfigurableBeanFactory) {
 			beanNames.addAll(Arrays.asList(((ConfigurableBeanFactory) this.beanFactory).getSingletonNames()));
 		}
+
 		for (String beanName : beanNames) {
 			if (!isExcluded(beanName) && !isBeanDefinitionAbstract(this.beanFactory, beanName)) {
 				try {
@@ -903,11 +891,11 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 					if (beanClass != null && callback.include(beanClass, beanName)) {
 						boolean lazyInit = isBeanDefinitionLazyInit(this.beanFactory, beanName);
 						Object beanInstance = (!lazyInit ? this.beanFactory.getBean(beanName) : null);
-						if (!ScopedProxyUtils.isScopedTarget(beanName) && !this.beans.containsValue(beanName) &&
+						if (!ScopedProxyUtils.isScopedTarget(beanName) && !beans.containsValue(beanName) &&
 								(beanInstance == null ||
-										!CollectionUtils.containsInstance(this.beans.values(), beanInstance))) {
+										!CollectionUtils.containsInstance(beans.values(), beanInstance))) {
 							// Not already registered for JMX exposure.
-							this.beans.put(beanName, (beanInstance != null ? beanInstance : beanName));
+							beans.put(beanName, (beanInstance != null ? beanInstance : beanName));
 							if (logger.isInfoEnabled()) {
 								logger.info("Bean with name '" + beanName + "' has been autodetected for JMX exposure");
 							}
@@ -970,6 +958,7 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	 */
 	private void registerNotificationListeners() throws MBeanExportException {
 		if (this.notificationListeners != null) {
+			Assert.state(this.server != null, "No MBeanServer available");
 			for (NotificationListenerBean bean : this.notificationListeners) {
 				try {
 					ObjectName[] mappedObjectNames = bean.getResolvedObjectNames();
@@ -996,19 +985,21 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	 * from the {@link MBeanServer}.
 	 */
 	private void unregisterNotificationListeners() {
-		this.registeredNotificationListeners.forEach((bean, mappedObjectNames) -> {
-			for (ObjectName mappedObjectName : mappedObjectNames) {
-				try {
-					this.server.removeNotificationListener(mappedObjectName, bean.getNotificationListener(),
-							bean.getNotificationFilter(), bean.getHandback());
-				}
-				catch (Throwable ex) {
-					if (logger.isDebugEnabled()) {
-						logger.debug("Unable to unregister NotificationListener", ex);
+		if (this.server != null) {
+			this.registeredNotificationListeners.forEach((bean, mappedObjectNames) -> {
+				for (ObjectName mappedObjectName : mappedObjectNames) {
+					try {
+						this.server.removeNotificationListener(mappedObjectName, bean.getNotificationListener(),
+								bean.getNotificationFilter(), bean.getHandback());
+					}
+					catch (Throwable ex) {
+						if (logger.isDebugEnabled()) {
+							logger.debug("Unable to unregister NotificationListener", ex);
+						}
 					}
 				}
-			}
-		});
+			});
+		}
 		this.registeredNotificationListeners.clear();
 	}
 
@@ -1096,8 +1087,10 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 	@SuppressWarnings("serial")
 	private class NotificationPublisherAwareLazyTargetSource extends LazyInitTargetSource {
 
+		@Nullable
 		private ModelMBean modelMBean;
 
+		@Nullable
 		private ObjectName objectName;
 
 		public void setModelMBean(ModelMBean modelMBean) {
@@ -1123,6 +1116,7 @@ public class MBeanExporter extends MBeanRegistrationSupport implements MBeanExpo
 
 		@Override
 		protected void postProcessTargetObject(Object targetObject) {
+			Assert.state(this.modelMBean != null && this.objectName != null, "Not initialized");
 			injectNotificationPublisherIfNecessary(targetObject, this.modelMBean, this.objectName);
 		}
 	}

spring-context/src/main/java/org/springframework/jmx/export/NotificationListenerBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -24,8 +24,7 @@ import org.springframework.util.Assert;
 
 /**
  * Helper class that aggregates a {@link javax.management.NotificationListener},
- * a {@link javax.management.NotificationFilter}, and an arbitrary handback
- * object.
+ * a {@link javax.management.NotificationFilter}, and an arbitrary handback object.
  *
  * <p>Also provides support for associating the encapsulated
  * {@link javax.management.NotificationListener} with any number of

spring-context/src/main/java/org/springframework/jmx/export/annotation/AnnotationJmxAttributeSource.java

@@ -50,6 +50,7 @@ import org.springframework.util.StringValueResolver;
  */
 public class AnnotationJmxAttributeSource implements JmxAttributeSource, BeanFactoryAware {
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
 

spring-context/src/main/java/org/springframework/jmx/export/assembler/AbstractConfigurableMBeanInfoAssembler.java

@@ -25,6 +25,7 @@ import javax.management.modelmbean.ModelMBeanNotificationInfo;
 
 import org.springframework.jmx.export.metadata.JmxMetadataUtils;
 import org.springframework.jmx.export.metadata.ManagedNotification;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -37,10 +38,10 @@ import org.springframework.util.StringUtils;
  */
 public abstract class AbstractConfigurableMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssembler {
 
+	@Nullable
 	private ModelMBeanNotificationInfo[] notificationInfos;
 
-	private final Map<String, ModelMBeanNotificationInfo[]> notificationInfoMappings =
-			new HashMap<>();
+	private final Map<String, ModelMBeanNotificationInfo[]> notificationInfoMappings = new HashMap<>();
 
 
 	public void setNotificationInfos(ManagedNotification[] notificationInfos) {

spring-context/src/main/java/org/springframework/jmx/export/assembler/InterfaceBasedMBeanInfoAssembler.java

@@ -61,14 +61,18 @@ import org.springframework.util.StringUtils;
 public class InterfaceBasedMBeanInfoAssembler extends AbstractConfigurableMBeanInfoAssembler
 		implements BeanClassLoaderAware, InitializingBean {
 
+	@Nullable
 	private Class<?>[] managedInterfaces;
 
 	/** Mappings of bean keys to an array of classes */
+	@Nullable
 	private Properties interfaceMappings;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
 	/** Mappings of bean keys to an array of classes */
+	@Nullable
 	private Map<String, Class<?>[]> resolvedInterfaceMappings;
 
 

spring-context/src/main/java/org/springframework/jmx/export/assembler/MetadataMBeanInfoAssembler.java

@@ -40,12 +40,12 @@ import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
 /**
- * Implementation of the {@link MBeanInfoAssembler}
- * interface that reads the management interface information from source level metadata.
+ * Implementation of the {@link MBeanInfoAssembler} interface that reads
+ * the management interface information from source level metadata.
  *
  * <p>Uses the {@link JmxAttributeSource} strategy interface, so that
  * metadata can be read using any supported implementation. Out of the box,
- * Spring provides an implementation based on JDK 1.5+ annotations,
+ * Spring provides an implementation based on annotations:
  * {@code AnnotationJmxAttributeSource}.
  *
  * @author Rob Harrop
@@ -58,6 +58,7 @@ import org.springframework.util.StringUtils;
 public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssembler
 		implements AutodetectCapableMBeanInfoAssembler, InitializingBean {
 
+	@Nullable
 	private JmxAttributeSource attributeSource;
 
 
@@ -96,6 +97,11 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 		}
 	}
 
+	private JmxAttributeSource obtainAttributeSource() {
+		Assert.state(this.attributeSource != null, "No JmxAttributeSource set");
+		return this.attributeSource;
+	}
+
 
 	/**
 	 * Throws an IllegalArgumentException if it encounters a JDK dynamic proxy.
@@ -118,7 +124,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 */
 	@Override
 	public boolean includeBean(Class<?> beanClass, String beanName) {
-		return (this.attributeSource.getManagedResource(getClassToExpose(beanClass)) != null);
+		return (obtainAttributeSource().getManagedResource(getClassToExpose(beanClass)) != null);
 	}
 
 	/**
@@ -164,14 +170,14 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 * Checks to see if the given Method has the {@code ManagedAttribute} attribute.
 	 */
 	private boolean hasManagedAttribute(Method method) {
-		return (this.attributeSource.getManagedAttribute(method) != null);
+		return (obtainAttributeSource().getManagedAttribute(method) != null);
 	}
 
 	/**
 	 * Checks to see if the given Method has the {@code ManagedMetric} attribute.
 	 */
 	private boolean hasManagedMetric(Method method) {
-		return (this.attributeSource.getManagedMetric(method) != null);
+		return (obtainAttributeSource().getManagedMetric(method) != null);
 	}
 
 	/**
@@ -179,7 +185,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 * @param method the method to check
 	 */
 	private boolean hasManagedOperation(Method method) {
-		return (this.attributeSource.getManagedOperation(method) != null);
+		return (obtainAttributeSource().getManagedOperation(method) != null);
 	}
 
 
@@ -189,7 +195,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 */
 	@Override
 	protected String getDescription(Object managedBean, String beanKey) {
-		ManagedResource mr = this.attributeSource.getManagedResource(getClassToExpose(managedBean));
+		ManagedResource mr = obtainAttributeSource().getManagedResource(getClassToExpose(managedBean));
 		return (mr != null ? mr.getDescription() : "");
 	}
 
@@ -204,9 +210,9 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 		Method writeMethod = propertyDescriptor.getWriteMethod();
 
 		ManagedAttribute getter =
-				(readMethod != null ? this.attributeSource.getManagedAttribute(readMethod) : null);
+				(readMethod != null ? obtainAttributeSource().getManagedAttribute(readMethod) : null);
 		ManagedAttribute setter =
-				(writeMethod != null ? this.attributeSource.getManagedAttribute(writeMethod) : null);
+				(writeMethod != null ? obtainAttributeSource().getManagedAttribute(writeMethod) : null);
 
 		if (getter != null && StringUtils.hasText(getter.getDescription())) {
 			return getter.getDescription();
@@ -215,7 +221,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 			return setter.getDescription();
 		}
 
-		ManagedMetric metric = (readMethod != null ? this.attributeSource.getManagedMetric(readMethod) : null);
+		ManagedMetric metric = (readMethod != null ? obtainAttributeSource().getManagedMetric(readMethod) : null);
 		if (metric != null && StringUtils.hasText(metric.getDescription())) {
 			return metric.getDescription();
 		}
@@ -231,18 +237,18 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	protected String getOperationDescription(Method method, String beanKey) {
 		PropertyDescriptor pd = BeanUtils.findPropertyForMethod(method);
 		if (pd != null) {
-			ManagedAttribute ma = this.attributeSource.getManagedAttribute(method);
+			ManagedAttribute ma = obtainAttributeSource().getManagedAttribute(method);
 			if (ma != null && StringUtils.hasText(ma.getDescription())) {
 				return ma.getDescription();
 			}
-			ManagedMetric metric = this.attributeSource.getManagedMetric(method);
+			ManagedMetric metric = obtainAttributeSource().getManagedMetric(method);
 			if (metric != null && StringUtils.hasText(metric.getDescription())) {
 				return metric.getDescription();
 			}
 			return method.getName();
 		}
 		else {
-			ManagedOperation mo = this.attributeSource.getManagedOperation(method);
+			ManagedOperation mo = obtainAttributeSource().getManagedOperation(method);
 			if (mo != null && StringUtils.hasText(mo.getDescription())) {
 				return mo.getDescription();
 			}
@@ -257,7 +263,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 */
 	@Override
 	protected MBeanParameterInfo[] getOperationParameters(Method method, String beanKey) {
-		ManagedOperationParameter[] params = this.attributeSource.getManagedOperationParameters(method);
+		ManagedOperationParameter[] params = obtainAttributeSource().getManagedOperationParameters(method);
 		if (ObjectUtils.isEmpty(params)) {
 			return super.getOperationParameters(method, beanKey);
 		}
@@ -279,7 +285,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	@Override
 	protected ModelMBeanNotificationInfo[] getNotificationInfo(Object managedBean, String beanKey) {
 		ManagedNotification[] notificationAttributes =
-				this.attributeSource.getManagedNotifications(getClassToExpose(managedBean));
+				obtainAttributeSource().getManagedNotifications(getClassToExpose(managedBean));
 		ModelMBeanNotificationInfo[] notificationInfos =
 				new ModelMBeanNotificationInfo[notificationAttributes.length];
 
@@ -299,7 +305,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 */
 	@Override
 	protected void populateMBeanDescriptor(Descriptor desc, Object managedBean, String beanKey) {
-		ManagedResource mr = this.attributeSource.getManagedResource(getClassToExpose(managedBean));
+		ManagedResource mr = obtainAttributeSource().getManagedResource(getClassToExpose(managedBean));
 		if (mr == null) {
 			throw new InvalidMetadataException(
 					"No ManagedResource attribute found for class: " + getClassToExpose(managedBean));
@@ -337,15 +343,15 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 			Descriptor desc, @Nullable Method getter, @Nullable Method setter, String beanKey) {
 
 		if (getter != null) {
-			ManagedMetric metric = this.attributeSource.getManagedMetric(getter);
+			ManagedMetric metric = obtainAttributeSource().getManagedMetric(getter);
 			if (metric != null) {
 				populateMetricDescriptor(desc, metric);
 				return;
 			}
 		}
 
-		ManagedAttribute gma = (getter != null ? this.attributeSource.getManagedAttribute(getter) : null);
-		ManagedAttribute sma = (setter != null ? this.attributeSource.getManagedAttribute(setter) : null);
+		ManagedAttribute gma = (getter != null ? obtainAttributeSource().getManagedAttribute(getter) : null);
+		ManagedAttribute sma = (setter != null ? obtainAttributeSource().getManagedAttribute(setter) : null);
 		populateAttributeDescriptor(desc,
 				(gma != null ? gma : ManagedAttribute.EMPTY),
 				(sma != null ? sma : ManagedAttribute.EMPTY));
@@ -399,7 +405,7 @@ public class MetadataMBeanInfoAssembler extends AbstractReflectiveMBeanInfoAssem
 	 */
 	@Override
 	protected void populateOperationDescriptor(Descriptor desc, Method method, String beanKey) {
-		ManagedOperation mo = this.attributeSource.getManagedOperation(method);
+		ManagedOperation mo = obtainAttributeSource().getManagedOperation(method);
 		if (mo != null) {
 			applyCurrencyTimeLimit(desc, mo.getCurrencyTimeLimit());
 		}

spring-context/src/main/java/org/springframework/jmx/export/assembler/MethodExclusionMBeanInfoAssembler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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 java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -57,8 +58,10 @@ import org.springframework.util.StringUtils;
  */
 public class MethodExclusionMBeanInfoAssembler extends AbstractConfigurableMBeanInfoAssembler {
 
+	@Nullable
 	private Set<String> ignoredMethods;
 
+	@Nullable
 	private Map<String, Set<String>> ignoredMethodMappings;
 
 

spring-context/src/main/java/org/springframework/jmx/export/assembler/MethodNameBasedMBeanInfoAssembler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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 java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -57,11 +58,13 @@ public class MethodNameBasedMBeanInfoAssembler extends AbstractConfigurableMBean
 	/**
 	 * Stores the set of method names to use for creating the management interface.
 	 */
+	@Nullable
 	private Set<String> managedMethods;
 
 	/**
 	 * Stores the mappings of bean keys to an array of method names.
 	 */
+	@Nullable
 	private Map<String, Set<String>> methodMappings;
 
 

spring-context/src/main/java/org/springframework/jmx/export/naming/KeyNamingStrategy.java

@@ -61,6 +61,7 @@ public class KeyNamingStrategy implements ObjectNamingStrategy, InitializingBean
 	/**
 	 * Stores the mappings of bean key to {@code ObjectName}.
 	 */
+	@Nullable
 	private Properties mappings;
 
 	/**
@@ -68,12 +69,14 @@ public class KeyNamingStrategy implements ObjectNamingStrategy, InitializingBean
 	 * into the final merged set of {@code Properties} used for {@code ObjectName}
 	 * resolution.
 	 */
+	@Nullable
 	private Resource[] mappingLocations;
 
 	/**
 	 * Stores the result of merging the {@code mappings} {@code Properties}
 	 * with the properties stored in the resources defined by {@code mappingLocations}.
 	 */
+	@Nullable
 	private Properties mergedMappings;
 
 

spring-context/src/main/java/org/springframework/jmx/export/naming/MetadataNamingStrategy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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 org.springframework.beans.factory.InitializingBean;
 import org.springframework.jmx.export.metadata.JmxAttributeSource;
 import org.springframework.jmx.export.metadata.ManagedResource;
 import org.springframework.jmx.support.ObjectNameManager;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
@@ -51,8 +52,10 @@ public class MetadataNamingStrategy implements ObjectNamingStrategy, Initializin
 	/**
 	 * The {@code JmxAttributeSource} implementation to use for reading metadata.
 	 */
+	@Nullable
 	private JmxAttributeSource attributeSource;
 
+	@Nullable
 	private String defaultDomain;
 
 
@@ -107,7 +110,8 @@ public class MetadataNamingStrategy implements ObjectNamingStrategy, Initializin
 	 * with the managed resource's {@code Class}.
 	 */
 	@Override
-	public ObjectName getObjectName(Object managedBean, String beanKey) throws MalformedObjectNameException {
+	public ObjectName getObjectName(Object managedBean, @Nullable String beanKey) throws MalformedObjectNameException {
+		Assert.state(this.attributeSource != null, "No JmxAttributeSource set");
 		Class<?> managedClass = AopUtils.getTargetClass(managedBean);
 		ManagedResource mr = this.attributeSource.getManagedResource(managedClass);
 
@@ -116,6 +120,7 @@ public class MetadataNamingStrategy implements ObjectNamingStrategy, Initializin
 			return ObjectNameManager.getInstance(mr.getObjectName());
 		}
 		else {
+			Assert.state(beanKey != null, "No ManagedResource attribute and no bean key specified");
 			try {
 				return ObjectNameManager.getInstance(beanKey);
 			}

spring-context/src/main/java/org/springframework/jmx/support/ConnectorServerFactoryBean.java

@@ -64,14 +64,17 @@ public class ConnectorServerFactoryBean extends MBeanRegistrationSupport
 
 	private Map<String, Object> environment = new HashMap<>();
 
+	@Nullable
 	private MBeanServerForwarder forwarder;
 
+	@Nullable
 	private ObjectName objectName;
 
 	private boolean threaded = false;
 
 	private boolean daemon = false;
 
+	@Nullable
 	private JMXConnectorServer connectorServer;
 
 
@@ -224,11 +227,13 @@ public class ConnectorServerFactoryBean extends MBeanRegistrationSupport
 	 */
 	@Override
 	public void destroy() throws IOException {
-		if (logger.isInfoEnabled()) {
-			logger.info("Stopping JMX connector server: " + this.connectorServer);
-		}
 		try {
-			this.connectorServer.stop();
+			if (this.connectorServer != null) {
+				if (logger.isInfoEnabled()) {
+					logger.info("Stopping JMX connector server: " + this.connectorServer);
+				}
+				this.connectorServer.stop();
+			}
 		}
 		finally {
 			unregisterBeans();

spring-context/src/main/java/org/springframework/jmx/support/MBeanRegistrationSupport.java

@@ -28,6 +28,7 @@ import javax.management.ObjectName;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -75,6 +76,7 @@ public class MBeanRegistrationSupport {
 	/**
 	 * The {@code MBeanServer} instance being used to register beans.
 	 */
+	@Nullable
 	protected MBeanServer server;
 
 	/**
@@ -101,6 +103,7 @@ public class MBeanRegistrationSupport {
 	/**
 	 * Return the {@code MBeanServer} that the beans will be registered with.
 	 */
+	@Nullable
 	public final MBeanServer getServer() {
 		return this.server;
 	}
@@ -125,6 +128,7 @@ public class MBeanRegistrationSupport {
 	 * @throws JMException if the registration failed
 	 */
 	protected void doRegister(Object mbean, ObjectName objectName) throws JMException {
+		Assert.state(this.server != null, "No MBeanServer set");
 		ObjectName actualObjectName;
 
 		synchronized (this.registeredBeans) {
@@ -188,6 +192,7 @@ public class MBeanRegistrationSupport {
 	 * @param objectName the suggested ObjectName for the MBean
 	 */
 	protected void doUnregister(ObjectName objectName) {
+		Assert.state(this.server != null, "No MBeanServer set");
 		boolean actuallyUnregistered = false;
 
 		synchronized (this.registeredBeans) {

spring-context/src/main/java/org/springframework/jmx/support/MBeanServerConnectionFactoryBean.java

@@ -34,6 +34,7 @@ import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
 
@@ -53,18 +54,23 @@ import org.springframework.util.CollectionUtils;
 public class MBeanServerConnectionFactoryBean
 		implements FactoryBean<MBeanServerConnection>, BeanClassLoaderAware, InitializingBean, DisposableBean {
 
+	@Nullable
 	private JMXServiceURL serviceUrl;
 
 	private Map<String, Object> environment = new HashMap<>();
 
 	private boolean connectOnStartup = true;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
+	@Nullable
 	private JMXConnector connector;
 
+	@Nullable
 	private MBeanServerConnection connection;
 
+	@Nullable
 	private JMXConnectorLazyInitTargetSource connectorTargetSource;
 
 
@@ -131,6 +137,7 @@ public class MBeanServerConnectionFactoryBean
 	 * environment properties.
 	 */
 	private void connect() throws IOException {
+		Assert.state(this.serviceUrl != null, "No JMXServiceURL set");
 		this.connector = JMXConnectorFactory.connect(this.serviceUrl, this.environment);
 		this.connection = this.connector.getMBeanServerConnection();
 	}
@@ -170,7 +177,8 @@ public class MBeanServerConnectionFactoryBean
 	 */
 	@Override
 	public void destroy() throws IOException {
-		if (this.connectorTargetSource == null || this.connectorTargetSource.isInitialized()) {
+		if (this.connector != null &&
+				(this.connectorTargetSource == null || this.connectorTargetSource.isInitialized())) {
 			this.connector.close();
 		}
 	}
@@ -186,6 +194,7 @@ public class MBeanServerConnectionFactoryBean
 
 		@Override
 		protected Object createObject() throws Exception {
+			Assert.state(serviceUrl != null, "No JMXServiceURL set");
 			return JMXConnectorFactory.connect(serviceUrl, environment);
 		}
 
@@ -203,6 +212,7 @@ public class MBeanServerConnectionFactoryBean
 
 		@Override
 		protected Object createObject() throws Exception {
+			Assert.state(connector != null, "JMXConnector not initialized");
 			return connector.getMBeanServerConnection();
 		}
 

spring-context/src/main/java/org/springframework/jmx/support/MBeanServerFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -58,12 +58,15 @@ public class MBeanServerFactoryBean implements FactoryBean<MBeanServer>, Initial
 
 	private boolean locateExistingServerIfPossible = false;
 
+	@Nullable
 	private String agentId;
 
+	@Nullable
 	private String defaultDomain;
 
 	private boolean registerWithFactory = true;
 
+	@Nullable
 	private MBeanServer server;
 
 	private boolean newlyRegistered = false;

spring-context/src/main/java/org/springframework/jmx/support/NotificationListenerHolder.java

@@ -41,12 +41,16 @@ import org.springframework.util.ObjectUtils;
  */
 public class NotificationListenerHolder {
 
+	@Nullable
 	private NotificationListener notificationListener;
 
+	@Nullable
 	private NotificationFilter notificationFilter;
 
+	@Nullable
 	private Object handback;
 
+	@Nullable
 	protected Set<Object> mappedObjectNames;
 
 

spring-context/src/main/java/org/springframework/jmx/support/WebSphereMBeanServerFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -23,6 +23,7 @@ import javax.management.MBeanServer;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.jmx.MBeanServerNotFoundException;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link FactoryBean} that obtains a WebSphere {@link javax.management.MBeanServer}
@@ -52,6 +53,7 @@ public class WebSphereMBeanServerFactoryBean implements FactoryBean<MBeanServer>
 	private static final String GET_MBEAN_SERVER_METHOD = "getMBeanServer";
 
 
+	@Nullable
 	private MBeanServer mbeanServer;
 
 

spring-context/src/main/java/org/springframework/jndi/JndiObjectFactoryBean.java

@@ -33,6 +33,8 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -70,6 +72,7 @@ import org.springframework.util.ClassUtils;
 public class JndiObjectFactoryBean extends JndiObjectLocator
 		implements FactoryBean<Object>, BeanFactoryAware, BeanClassLoaderAware {
 
+	@Nullable
 	private Class<?>[] proxyInterfaces;
 
 	private boolean lookupOnStartup = true;
@@ -78,12 +81,16 @@ public class JndiObjectFactoryBean extends JndiObjectLocator
 
 	private boolean exposeAccessContext = false;
 
+	@Nullable
 	private Object defaultObject;
 
+	@Nullable
 	private ConfigurableBeanFactory beanFactory;
 
+	@Nullable
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
 
+	@Nullable
 	private Object jndiObject;
 
 
@@ -310,7 +317,9 @@ public class JndiObjectFactoryBean extends JndiObjectLocator
 			// Create a JndiObjectTargetSource that mirrors the JndiObjectFactoryBean's configuration.
 			JndiObjectTargetSource targetSource = new JndiObjectTargetSource();
 			targetSource.setJndiTemplate(jof.getJndiTemplate());
-			targetSource.setJndiName(jof.getJndiName());
+			String jndiName = jof.getJndiName();
+			Assert.state(jndiName != null, "No JNDI name specified");
+			targetSource.setJndiName(jndiName);
 			targetSource.setExpectedType(jof.getExpectedType());
 			targetSource.setResourceRef(jof.isResourceRef());
 			targetSource.setLookupOnStartup(jof.lookupOnStartup);

spring-context/src/main/java/org/springframework/jndi/JndiObjectLocator.java

@@ -20,6 +20,7 @@ import javax.naming.NamingException;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -48,8 +49,10 @@ import org.springframework.util.StringUtils;
  */
 public abstract class JndiObjectLocator extends JndiLocatorSupport implements InitializingBean {
 
+	@Nullable
 	private String jndiName;
 
+	@Nullable
 	private Class<?> expectedType;
 
 
@@ -66,6 +69,7 @@ public abstract class JndiObjectLocator extends JndiLocatorSupport implements In
 	/**
 	 * Return the JNDI name to look up.
 	 */
+	@Nullable
 	public String getJndiName() {
 		return this.jndiName;
 	}
@@ -105,7 +109,9 @@ public abstract class JndiObjectLocator extends JndiLocatorSupport implements In
 	 * @see #lookup(String, Class)
 	 */
 	protected Object lookup() throws NamingException {
-		return lookup(getJndiName(), getExpectedType());
+		String jndiName = getJndiName();
+		Assert.state(jndiName != null, "No JNDI name specified");
+		return lookup(jndiName, getExpectedType());
 	}
 
 }

spring-context/src/main/java/org/springframework/jndi/JndiObjectTargetSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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 @@ package org.springframework.jndi;
 import javax.naming.NamingException;
 
 import org.springframework.aop.TargetSource;
+import org.springframework.lang.Nullable;
 
 /**
  * AOP {@link org.springframework.aop.TargetSource} that provides
@@ -64,8 +65,10 @@ public class JndiObjectTargetSource extends JndiObjectLocator implements TargetS
 
 	private boolean cache = true;
 
+	@Nullable
 	private Object cachedObject;
 
+	@Nullable
 	private Class<?> targetClass;
 
 

spring-context/src/main/java/org/springframework/jndi/JndiTemplate.java

@@ -43,6 +43,7 @@ public class JndiTemplate {
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private Properties environment;
 
 

spring-context/src/main/java/org/springframework/scheduling/annotation/AbstractAsyncConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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 org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportAware;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -39,10 +40,13 @@ import org.springframework.util.CollectionUtils;
 @Configuration
 public abstract class AbstractAsyncConfiguration implements ImportAware {
 
+	@Nullable
 	protected AnnotationAttributes enableAsync;
 
+	@Nullable
 	protected Executor executor;
 
+	@Nullable
 	protected AsyncUncaughtExceptionHandler exceptionHandler;
 
 

spring-context/src/main/java/org/springframework/scheduling/annotation/AsyncAnnotationAdvisor.java

@@ -152,7 +152,6 @@ public class AsyncAnnotationAdvisor extends AbstractPointcutAdvisor implements B
 	 * @param asyncAnnotationTypes the async annotation types to introspect
 	 * @return the applicable Pointcut object, or {@code null} if none
 	 */
-	@Nullable
 	protected Pointcut buildPointcut(Set<Class<? extends Annotation>> asyncAnnotationTypes) {
 		ComposablePointcut result = null;
 		for (Class<? extends Annotation> asyncAnnotationType : asyncAnnotationTypes) {
@@ -166,7 +165,7 @@ public class AsyncAnnotationAdvisor extends AbstractPointcutAdvisor implements B
 			}
 			result = result.union(mpc);
 		}
-		return result;
+		return (result != null ? result : Pointcut.TRUE);
 	}
 
 }

spring-context/src/main/java/org/springframework/scheduling/annotation/AsyncAnnotationBeanPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -26,6 +26,7 @@ import org.springframework.aop.framework.autoproxy.AbstractBeanFactoryAwareAdvis
 import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.core.task.TaskExecutor;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -74,10 +75,13 @@ public class AsyncAnnotationBeanPostProcessor extends AbstractBeanFactoryAwareAd
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private Class<? extends Annotation> asyncAnnotationType;
 
+	@Nullable
 	private Executor executor;
 
+	@Nullable
 	private AsyncUncaughtExceptionHandler exceptionHandler;
 
 

spring-context/src/main/java/org/springframework/scheduling/annotation/AsyncResult.java

@@ -47,8 +47,10 @@ import org.springframework.util.concurrent.SuccessCallback;
  */
 public class AsyncResult<V> implements ListenableFuture<V> {
 
+	@Nullable
 	private final V value;
 
+	@Nullable
 	private final Throwable executionException;
 
 
@@ -86,6 +88,7 @@ public class AsyncResult<V> implements ListenableFuture<V> {
 	}
 
 	@Override
+	@Nullable
 	public V get() throws ExecutionException {
 		if (this.executionException != null) {
 			throw (this.executionException instanceof ExecutionException ?
@@ -96,6 +99,7 @@ public class AsyncResult<V> implements ListenableFuture<V> {
 	}
 
 	@Override
+	@Nullable
 	public V get(long timeout, TimeUnit unit) throws ExecutionException {
 		return get();
 	}

spring-context/src/main/java/org/springframework/scheduling/annotation/ScheduledAnnotationBeanPostProcessor.java

@@ -53,6 +53,7 @@ import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.scheduling.Trigger;
 import org.springframework.scheduling.config.CronTask;
@@ -107,14 +108,19 @@ public class ScheduledAnnotationBeanPostProcessor
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private Object scheduler;
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
+	@Nullable
 	private String beanName;
 
+	@Nullable
 	private BeanFactory beanFactory;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 	private final ScheduledTaskRegistrar registrar = new ScheduledTaskRegistrar();
@@ -216,12 +222,12 @@ public class ScheduledAnnotationBeanPostProcessor
 			Assert.state(this.beanFactory != null, "BeanFactory must be set to find scheduler by type");
 			try {
 				// Search for TaskScheduler bean...
-				this.registrar.setTaskScheduler(resolveSchedulerBean(TaskScheduler.class, false));
+				this.registrar.setTaskScheduler(resolveSchedulerBean(beanFactory, TaskScheduler.class, false));
 			}
 			catch (NoUniqueBeanDefinitionException ex) {
 				logger.debug("Could not find unique TaskScheduler bean", ex);
 				try {
-					this.registrar.setTaskScheduler(resolveSchedulerBean(TaskScheduler.class, true));
+					this.registrar.setTaskScheduler(resolveSchedulerBean(beanFactory, TaskScheduler.class, true));
 				}
 				catch (NoSuchBeanDefinitionException ex2) {
 					if (logger.isInfoEnabled()) {
@@ -237,12 +243,12 @@ public class ScheduledAnnotationBeanPostProcessor
 				logger.debug("Could not find default TaskScheduler bean", ex);
 				// Search for ScheduledExecutorService bean next...
 				try {
-					this.registrar.setScheduler(resolveSchedulerBean(ScheduledExecutorService.class, false));
+					this.registrar.setScheduler(resolveSchedulerBean(beanFactory, ScheduledExecutorService.class, false));
 				}
 				catch (NoUniqueBeanDefinitionException ex2) {
 					logger.debug("Could not find unique ScheduledExecutorService bean", ex2);
 					try {
-						this.registrar.setScheduler(resolveSchedulerBean(ScheduledExecutorService.class, true));
+						this.registrar.setScheduler(resolveSchedulerBean(beanFactory, ScheduledExecutorService.class, true));
 					}
 					catch (NoSuchBeanDefinitionException ex3) {
 						if (logger.isInfoEnabled()) {
@@ -265,25 +271,24 @@ public class ScheduledAnnotationBeanPostProcessor
 		this.registrar.afterPropertiesSet();
 	}
 
-	private <T> T resolveSchedulerBean(Class<T> schedulerType, boolean byName) {
+	private <T> T resolveSchedulerBean(BeanFactory beanFactory, Class<T> schedulerType, boolean byName) {
 		if (byName) {
-			T scheduler = this.beanFactory.getBean(DEFAULT_TASK_SCHEDULER_BEAN_NAME, schedulerType);
-			if (this.beanFactory instanceof ConfigurableBeanFactory) {
+			T scheduler = beanFactory.getBean(DEFAULT_TASK_SCHEDULER_BEAN_NAME, schedulerType);
+			if (this.beanName != null && this.beanFactory instanceof ConfigurableBeanFactory) {
 				((ConfigurableBeanFactory) this.beanFactory).registerDependentBean(
 						DEFAULT_TASK_SCHEDULER_BEAN_NAME, this.beanName);
 			}
 			return scheduler;
 		}
-		else if (this.beanFactory instanceof AutowireCapableBeanFactory) {
-			NamedBeanHolder<T> holder = ((AutowireCapableBeanFactory) this.beanFactory).resolveNamedBean(schedulerType);
-			if (this.beanFactory instanceof ConfigurableBeanFactory) {
-				((ConfigurableBeanFactory) this.beanFactory).registerDependentBean(
-						holder.getBeanName(), this.beanName);
+		else if (beanFactory instanceof AutowireCapableBeanFactory) {
+			NamedBeanHolder<T> holder = ((AutowireCapableBeanFactory) beanFactory).resolveNamedBean(schedulerType);
+			if (this.beanName != null && beanFactory instanceof ConfigurableBeanFactory) {
+				((ConfigurableBeanFactory) beanFactory).registerDependentBean(holder.getBeanName(), this.beanName);
 			}
 			return holder.getBeanInstance();
 		}
 		else {
-			return this.beanFactory.getBean(schedulerType);
+			return beanFactory.getBean(schedulerType);
 		}
 	}
 

spring-context/src/main/java/org/springframework/scheduling/concurrent/ConcurrentTaskExecutor.java

@@ -63,6 +63,7 @@ import org.springframework.util.concurrent.ListenableFuture;
  */
 public class ConcurrentTaskExecutor implements AsyncListenableTaskExecutor, SchedulingTaskExecutor {
 
+	@Nullable
 	private static Class<?> managedExecutorServiceClass;
 
 	static {

spring-context/src/main/java/org/springframework/scheduling/concurrent/ConcurrentTaskScheduler.java

@@ -65,6 +65,7 @@ import org.springframework.util.ErrorHandler;
  */
 public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements TaskScheduler {
 
+	@Nullable
 	private static Class<?> managedScheduledExecutorServiceClass;
 
 	static {
@@ -79,10 +80,12 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 		}
 	}
 
+
 	private ScheduledExecutorService scheduledExecutor;
 
 	private boolean enterpriseConcurrentScheduler = false;
 
+	@Nullable
 	private ErrorHandler errorHandler;
 
 
@@ -93,7 +96,7 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler() {
 		super();
-		setScheduledExecutor(null);
+		this.scheduledExecutor = initScheduledExecutor(null);
 	}
 
 	/**
@@ -108,7 +111,7 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler(ScheduledExecutorService scheduledExecutor) {
 		super(scheduledExecutor);
-		setScheduledExecutor(scheduledExecutor);
+		this.scheduledExecutor = initScheduledExecutor(scheduledExecutor);
 	}
 
 	/**
@@ -124,10 +127,23 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 */
 	public ConcurrentTaskScheduler(Executor concurrentExecutor, ScheduledExecutorService scheduledExecutor) {
 		super(concurrentExecutor);
-		setScheduledExecutor(scheduledExecutor);
+		this.scheduledExecutor = initScheduledExecutor(scheduledExecutor);
 	}
 
 
+	private ScheduledExecutorService initScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
+		if (scheduledExecutor != null) {
+			this.scheduledExecutor = scheduledExecutor;
+			this.enterpriseConcurrentScheduler = (managedScheduledExecutorServiceClass != null &&
+					managedScheduledExecutorServiceClass.isInstance(scheduledExecutor));
+		}
+		else {
+			this.scheduledExecutor = Executors.newSingleThreadScheduledExecutor();
+			this.enterpriseConcurrentScheduler = false;
+		}
+		return this.scheduledExecutor;
+	}
+
 	/**
 	 * Specify the {@link java.util.concurrent.ScheduledExecutorService} to delegate to.
 	 * <p>Autodetects a JSR-236 {@link javax.enterprise.concurrent.ManagedScheduledExecutorService}
@@ -139,16 +155,8 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 	 * as well, pass the same executor reference to {@link #setConcurrentExecutor}.
 	 * @see #setConcurrentExecutor
 	 */
-	public final void setScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
-		if (scheduledExecutor != null) {
-			this.scheduledExecutor = scheduledExecutor;
-			this.enterpriseConcurrentScheduler = (managedScheduledExecutorServiceClass != null &&
-					managedScheduledExecutorServiceClass.isInstance(scheduledExecutor));
-		}
-		else {
-			this.scheduledExecutor = Executors.newSingleThreadScheduledExecutor();
-			this.enterpriseConcurrentScheduler = false;
-		}
+	public void setScheduledExecutor(@Nullable ScheduledExecutorService scheduledExecutor) {
+		initScheduledExecutor(scheduledExecutor);
 	}
 
 	/**
@@ -167,7 +175,8 @@ public class ConcurrentTaskScheduler extends ConcurrentTaskExecutor implements T
 				return new EnterpriseConcurrentTriggerScheduler().schedule(decorateTask(task, true), trigger);
 			}
 			else {
-				ErrorHandler errorHandler = (this.errorHandler != null ? this.errorHandler : TaskUtils.getDefaultErrorHandler(true));
+				ErrorHandler errorHandler =
+						(this.errorHandler != null ? this.errorHandler : TaskUtils.getDefaultErrorHandler(true));
 				return new ReschedulingRunnable(task, trigger, this.scheduledExecutor, errorHandler).schedule();
 			}
 		}

spring-context/src/main/java/org/springframework/scheduling/concurrent/DefaultManagedAwareThreadFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -26,6 +26,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.jndi.JndiLocatorDelegate;
 import org.springframework.jndi.JndiTemplate;
+import org.springframework.lang.Nullable;
 
 /**
  * JNDI-based variant of {@link CustomizableThreadFactory}, performing a default lookup
@@ -51,8 +52,10 @@ public class DefaultManagedAwareThreadFactory extends CustomizableThreadFactory
 
 	private JndiLocatorDelegate jndiLocator = new JndiLocatorDelegate();
 
+	@Nullable
 	private String jndiName = "java:comp/DefaultManagedThreadFactory";
 
+	@Nullable
 	private ThreadFactory threadFactory;