Various DefaultListableBeanFactory clarifications

* getBeanDefinitionNames defensively returns a copy of the bean definition names array.
* copyConfigurationFrom provides an independent AutowireCandidateResolver instance and copies a ConversionService and dependency comparator configuration as well.
* findAutowireCandidates only considers a self reference fallback for direct dependency declarations, not as a collection element.

Issue: SPR-14897
Issue: SPR-14921
Issue: SPR-14965

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java

@@ -131,16 +131,14 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 	private ConversionService conversionService;
 
 	/** Custom PropertyEditorRegistrars to apply to the beans of this factory */
-	private final Set<PropertyEditorRegistrar> propertyEditorRegistrars =
+	private final Set<PropertyEditorRegistrar> propertyEditorRegistrars = new LinkedHashSet<>(4);
-			new LinkedHashSet<>(4);
+
+	/** Custom PropertyEditors to apply to the beans of this factory */
+	private final Map<Class<?>, Class<? extends PropertyEditor>> customEditors = new HashMap<>(4);
 
 	/** A custom TypeConverter to use, overriding the default PropertyEditor mechanism */
 	private TypeConverter typeConverter;
 
-	/** Custom PropertyEditors to apply to the beans of this factory */
-	private final Map<Class<?>, Class<? extends PropertyEditor>> customEditors =
-			new HashMap<>(4);
-
 	/** String resolvers to apply e.g. to annotation attribute values */
 	private final List<StringValueResolver> embeddedValueResolvers = new LinkedList<>();
 
@@ -919,10 +917,12 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 		setBeanClassLoader(otherFactory.getBeanClassLoader());
 		setCacheBeanMetadata(otherFactory.isCacheBeanMetadata());
 		setBeanExpressionResolver(otherFactory.getBeanExpressionResolver());
+		setConversionService(otherFactory.getConversionService());
 		if (otherFactory instanceof AbstractBeanFactory) {
 			AbstractBeanFactory otherAbstractFactory = (AbstractBeanFactory) otherFactory;
-			this.customEditors.putAll(otherAbstractFactory.customEditors);
 			this.propertyEditorRegistrars.addAll(otherAbstractFactory.propertyEditorRegistrars);
+			this.customEditors.putAll(otherAbstractFactory.customEditors);
+			this.typeConverter = otherAbstractFactory.typeConverter;
 			this.beanPostProcessors.addAll(otherAbstractFactory.beanPostProcessors);
 			this.hasInstantiationAwareBeanPostProcessors = this.hasInstantiationAwareBeanPostProcessors ||
 					otherAbstractFactory.hasInstantiationAwareBeanPostProcessors;
@@ -933,6 +933,10 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 		}
 		else {
 			setTypeConverter(otherFactory.getTypeConverter());
+			String[] otherScopeNames = otherFactory.getRegisteredScopeNames();
+			for (String scopeName : otherScopeNames) {
+				this.scopes.put(scopeName, otherFactory.getRegisteredScope(scopeName));
+			}
 		}
 	}
 

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultListableBeanFactory.java

@@ -43,6 +43,7 @@ import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import javax.inject.Provider;
 
+import org.springframework.beans.BeanUtils;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.TypeConverter;
 import org.springframework.beans.factory.BeanCreationException;
@@ -256,6 +257,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 
 	/**
 	 * Set a {@link java.util.Comparator} for dependency Lists and arrays.
+	 * @since 4.0
 	 * @see org.springframework.core.OrderComparator
 	 * @see org.springframework.core.annotation.AnnotationAwareOrderComparator
 	 */
@@ -265,6 +267,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 
 	/**
 	 * Return the dependency comparator for this BeanFactory (may be {@code null}.
+	 * @since 4.0
 	 */
 	public Comparator<Object> getDependencyComparator() {
 		return this.dependencyComparator;
@@ -279,11 +282,10 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 		Assert.notNull(autowireCandidateResolver, "AutowireCandidateResolver must not be null");
 		if (autowireCandidateResolver instanceof BeanFactoryAware) {
 			if (System.getSecurityManager() != null) {
-				final BeanFactory target = this;
 				AccessController.doPrivileged(new PrivilegedAction<Object>() {
 					@Override
 					public Object run() {
-						((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(target);
+						((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(DefaultListableBeanFactory.this);
 						return null;
 					}
 				}, getAccessControlContext());
@@ -310,7 +312,10 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 			DefaultListableBeanFactory otherListableFactory = (DefaultListableBeanFactory) otherFactory;
 			this.allowBeanDefinitionOverriding = otherListableFactory.allowBeanDefinitionOverriding;
 			this.allowEagerClassLoading = otherListableFactory.allowEagerClassLoading;
-			this.autowireCandidateResolver = otherListableFactory.autowireCandidateResolver;
+			this.dependencyComparator = otherListableFactory.dependencyComparator;
+			// A clone of the AutowireCandidateResolver since it is potentially BeanFactoryAware...
+			setAutowireCandidateResolver(BeanUtils.instantiateClass(getAutowireCandidateResolver().getClass()));
+			// Make resolvable dependencies (e.g. ResourceLoader) available here as well...
 			this.resolvableDependencies.putAll(otherListableFactory.resolvableDependencies);
 		}
 	}
@@ -357,7 +362,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 	@Override
 	public String[] getBeanDefinitionNames() {
 		if (this.frozenBeanDefinitionNames != null) {
-			return this.frozenBeanDefinitionNames;
+			return this.frozenBeanDefinitionNames.clone();
 		}
 		else {
 			return StringUtils.toStringArray(this.beanDefinitionNames);
@@ -1256,8 +1261,9 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 					addCandidateEntry(result, candidateName, descriptor, requiredType);
 				}
 			}
-			if (result.isEmpty()) {
+			if (result.isEmpty() && !(descriptor instanceof MultiElementDependencyDescriptor)) {
-				// Consider self references before as a final pass
+				// Consider self references as a final pass...
+				// but not as collection elements, just for direct dependency declarations.
 				for (String candidateName : candidateNames) {
 					if (isSelfReference(beanName, candidateName) && isAutowireCandidate(candidateName, fallbackDescriptor)) {
 						addCandidateEntry(result, candidateName, descriptor, requiredType);
@@ -1466,10 +1472,10 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 			Class<?> targetType = mbd.getTargetType();
 			if (targetType != null && type.isAssignableFrom(targetType) &&
 					isAutowireCandidate(beanName, mbd, descriptor, getAutowireCandidateResolver())) {
-				// Probably a poxy interfering with target type match -> throw meaningful exception.
+				// Probably a proxy interfering with target type match -> throw meaningful exception.
 				Object beanInstance = getSingleton(beanName, false);
 				Class<?> beanType = (beanInstance != null ? beanInstance.getClass() : predictBeanType(beanName, mbd));
-				if (type != beanType) {
+				if (!type.isAssignableFrom((beanType))) {
 					throw new BeanNotOfRequiredTypeException(beanName, type, beanType);
 				}
 			}

spring-beans/src/test/java/org/springframework/beans/factory/DefaultListableBeanFactoryTests.java

@@ -776,6 +776,7 @@ public class DefaultListableBeanFactoryTests {
 	private void testSingleTestBean(ListableBeanFactory lbf) {
 		assertTrue("1 beans defined", lbf.getBeanDefinitionCount() == 1);
 		String[] names = lbf.getBeanDefinitionNames();
+		assertTrue(names != lbf.getBeanDefinitionNames());
 		assertTrue("Array length == 1", names.length == 1);
 		assertTrue("0th element == test", names[0].equals("test"));
 		TestBean tb = (TestBean) lbf.getBean("test");

spring-beans/src/test/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessorTests.java

@@ -29,6 +29,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -978,11 +979,59 @@ public class AutowiredAnnotationBeanPostProcessorTests {
 		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
 		bpp.setBeanFactory(bf);
 		bf.addBeanPostProcessor(bpp);
-		RootBeanDefinition bd = new RootBeanDefinition(SelfInjectionBean.class);
+		bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(SelfInjectionBean.class));
-		bf.registerBeanDefinition("annotatedBean", bd);
+
+		SelfInjectionBean bean = (SelfInjectionBean) bf.getBean("annotatedBean");
+		assertSame(bean, bean.reference);
+		assertNull(bean.referenceCollection);
+	}
+
+	@Test
+	public void testSelfReferenceWithOther() {
+		DefaultListableBeanFactory bf = new DefaultListableBeanFactory();
+		bf.setAutowireCandidateResolver(new QualifierAnnotationAutowireCandidateResolver());
+		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
+		bpp.setBeanFactory(bf);
+		bf.addBeanPostProcessor(bpp);
+		bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(SelfInjectionBean.class));
+		bf.registerBeanDefinition("annotatedBean2", new RootBeanDefinition(SelfInjectionBean.class));
 
 		SelfInjectionBean bean = (SelfInjectionBean) bf.getBean("annotatedBean");
-		assertSame(bean, bean.selfReference);
+		SelfInjectionBean bean2 = (SelfInjectionBean) bf.getBean("annotatedBean2");
+		assertSame(bean2, bean.reference);
+		assertEquals(1, bean.referenceCollection.size());
+		assertSame(bean2, bean.referenceCollection.get(0));
+	}
+
+	@Test
+	public void testSelfReferenceCollection() {
+		DefaultListableBeanFactory bf = new DefaultListableBeanFactory();
+		bf.setAutowireCandidateResolver(new QualifierAnnotationAutowireCandidateResolver());
+		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
+		bpp.setBeanFactory(bf);
+		bf.addBeanPostProcessor(bpp);
+		bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(SelfInjectionCollectionBean.class));
+
+		SelfInjectionCollectionBean bean = (SelfInjectionCollectionBean) bf.getBean("annotatedBean");
+		assertSame(bean, bean.reference);
+		assertNull(bean.referenceCollection);
+	}
+
+	@Test
+	public void testSelfReferenceCollectionWithOther() {
+		DefaultListableBeanFactory bf = new DefaultListableBeanFactory();
+		bf.setAutowireCandidateResolver(new QualifierAnnotationAutowireCandidateResolver());
+		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
+		bpp.setBeanFactory(bf);
+		bf.addBeanPostProcessor(bpp);
+		bf.registerBeanDefinition("annotatedBean", new RootBeanDefinition(SelfInjectionCollectionBean.class));
+		bf.registerBeanDefinition("annotatedBean2", new RootBeanDefinition(SelfInjectionCollectionBean.class));
+
+		SelfInjectionCollectionBean bean = (SelfInjectionCollectionBean) bf.getBean("annotatedBean");
+		SelfInjectionCollectionBean bean2 = (SelfInjectionCollectionBean) bf.getBean("annotatedBean2");
+		assertSame(bean2, bean.reference);
+		assertSame(1, bean2.referenceCollection.size());
+		assertSame(bean2, bean.referenceCollection.get(0));
 	}
 
 	@Test
@@ -2582,7 +2631,21 @@ public class AutowiredAnnotationBeanPostProcessorTests {
 	public static class SelfInjectionBean {
 
 		@Autowired
-		public SelfInjectionBean selfReference;
+		public SelfInjectionBean reference;
+
+		@Autowired(required = false)
+		public List<SelfInjectionBean> referenceCollection;
+	}
+
+
+	@SuppressWarnings("serial")
+	public static class SelfInjectionCollectionBean extends LinkedList<SelfInjectionCollectionBean> {
+
+		@Autowired
+		public SelfInjectionCollectionBean reference;
+
+		@Autowired(required = false)
+		public List<SelfInjectionCollectionBean> referenceCollection;
 	}