DefaultListableBeanFactory checks for pre-converted Optional wrappers

Issue: SPR-17607

Author: jhoeller

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -1549,7 +1549,8 @@ public Object resolveCandidate(String beanName, Class<?> requiredType, BeanFacto
 						super.resolveCandidate(beanName, requiredType, beanFactory));
 			}
 		};
-		return Optional.ofNullable(doResolveDependency(descriptorToUse, beanName, null, null));
+		Object result = doResolveDependency(descriptorToUse, beanName, null, null);
+		return (result instanceof Optional ? (Optional<?>) result : Optional.ofNullable(result));
 	}
 
 
@@ -1630,7 +1631,7 @@ public NestedDependencyDescriptor(DependencyDescriptor original) {
 
 
 	/**
-	 * A dependency descriptor marker for multiple elements.
+	 * A dependency descriptor for a multi-element declaration with nested elements.
 	 */
 	private static class MultiElementDescriptor extends NestedDependencyDescriptor {
 

spring-context/src/test/java/org/springframework/context/expression/ApplicationContextExpressionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -25,11 +25,11 @@
 import java.net.URL;
 import java.security.AccessControlException;
 import java.security.Permission;
+import java.util.Optional;
 import java.util.Properties;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.junit.Test;
 
 import org.springframework.beans.factory.ObjectFactory;
@@ -46,7 +46,7 @@
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigUtils;
 import org.springframework.context.support.GenericApplicationContext;
-import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.convert.support.GenericConversionService;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
@@ -102,6 +102,8 @@ public String getConversationId() {
 			}
 		});
 
+		ac.getBeanFactory().setConversionService(new DefaultConversionService());
+
 		PropertyPlaceholderConfigurer ppc = new PropertyPlaceholderConfigurer();
 		Properties placeholders = new Properties();
 		placeholders.setProperty("code", "123");
@@ -176,6 +178,9 @@ public String getConversationId() {
 			System.getProperties().put("country", "UK");
 			assertEquals("123 UK", tb3.country);
 			assertEquals("123 UK", tb3.countryFactory.getObject());
+			assertEquals("123", tb3.optionalValue1.get());
+			assertEquals("123", tb3.optionalValue2.get());
+			assertFalse(tb3.optionalValue3.isPresent());
 			assertSame(tb0, tb3.tb);
 
 			tb3 = (ValueTestBean) SerializationTestUtils.serializeAndDeserialize(tb3);
@@ -209,12 +214,7 @@ public void prototypeCreationReevaluatesExpressions() {
 		GenericApplicationContext ac = new GenericApplicationContext();
 		AnnotationConfigUtils.registerAnnotationConfigProcessors(ac);
 		GenericConversionService cs = new GenericConversionService();
-		cs.addConverter(String.class, String.class, new Converter<String, String>() {
-			@Override
-			public String convert(String source) {
-				return source.trim();
-			}
-		});
+		cs.addConverter(String.class, String.class, String::trim);
 		ac.getBeanFactory().registerSingleton(GenericApplicationContext.CONVERSION_SERVICE_BEAN_NAME, cs);
 		RootBeanDefinition rbd = new RootBeanDefinition(PrototypeTestBean.class);
 		rbd.setScope(RootBeanDefinition.SCOPE_PROTOTYPE);
@@ -276,8 +276,7 @@ public void prototypeCreationIsFastEnough() {
 
 	@Test
 	public void systemPropertiesSecurityManager() {
-		GenericApplicationContext ac = new GenericApplicationContext();
-		AnnotationConfigUtils.registerAnnotationConfigProcessors(ac);
+		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext();
 
 		GenericBeanDefinition bd = new GenericBeanDefinition();
 		bd.setBeanClass(TestBean.class);
@@ -313,8 +312,7 @@ public void checkPermission(Permission perm) {
 
 	@Test
 	public void stringConcatenationWithDebugLogging() {
-		GenericApplicationContext ac = new GenericApplicationContext();
-		AnnotationConfigUtils.registerAnnotationConfigProcessors(ac);
+		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext();
 
 		GenericBeanDefinition bd = new GenericBeanDefinition();
 		bd.setBeanClass(String.class);
@@ -365,6 +363,15 @@ public static class ValueTestBean implements Serializable {
 		@Value("${code} #{systemProperties.country}")
 		public ObjectFactory<String> countryFactory;
 
+		@Value("${code}")
+		private transient Optional<String> optionalValue1;
+
+		@Value("${code:#{null}}")
+		private transient Optional<String> optionalValue2;
+
+		@Value("${codeX:#{null}}")
+		private transient Optional<String> optionalValue3;
+
 		@Autowired @Qualifier("original")
 		public transient TestBean tb;
 	}

spring-core/src/main/java/org/springframework/core/convert/TypeDescriptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -80,7 +80,7 @@ public class TypeDescriptor implements Serializable {
 	 */
 	public TypeDescriptor(MethodParameter methodParameter) {
 		this.resolvableType = ResolvableType.forMethodParameter(methodParameter);
-		this.type = this.resolvableType.resolve(methodParameter.getParameterType());
+		this.type = this.resolvableType.resolve(methodParameter.getNestedParameterType());
 		this.annotatedElement = new AnnotatedElementAdapter(methodParameter.getParameterIndex() == -1 ?
 				methodParameter.getMethodAnnotations() : methodParameter.getParameterAnnotations());
 	}
@@ -616,7 +616,7 @@ public static TypeDescriptor array(@Nullable TypeDescriptor elementTypeDescripto
 	}
 
 	/**
-	 * Creates a type descriptor for a nested type declared within the method parameter.
+	 * Create a type descriptor for a nested type declared within the method parameter.
 	 * <p>For example, if the methodParameter is a {@code List<String>} and the
 	 * nesting level is 1, the nested type descriptor will be String.class.
 	 * <p>If the methodParameter is a {@code List<List<String>>} and the nesting
@@ -647,7 +647,7 @@ public static TypeDescriptor nested(MethodParameter methodParameter, int nesting
 	}
 
 	/**
-	 * Creates a type descriptor for a nested type declared within the field.
+	 * Create a type descriptor for a nested type declared within the field.
 	 * <p>For example, if the field is a {@code List<String>} and the nesting
 	 * level is 1, the nested type descriptor will be {@code String.class}.
 	 * <p>If the field is a {@code List<List<String>>} and the nesting level is
@@ -656,8 +656,9 @@ public static TypeDescriptor nested(MethodParameter methodParameter, int nesting
 	 * is 1, the nested type descriptor will be String, derived from the map value.
 	 * <p>If the field is a {@code List<Map<Integer, String>>} and the nesting
 	 * level is 2, the nested type descriptor will be String, derived from the map value.
-	 * <p>Returns {@code null} if a nested type cannot be obtained because it was not declared.
-	 * For example, if the field is a {@code List<?>}, the nested type descriptor returned will be {@code null}.
+	 * <p>Returns {@code null} if a nested type cannot be obtained because it was not
+	 * declared. For example, if the field is a {@code List<?>}, the nested type
+	 * descriptor returned will be {@code null}.
 	 * @param field the field
 	 * @param nestingLevel the nesting level of the collection/array element or
 	 * map key/value declaration within the field
@@ -672,7 +673,7 @@ public static TypeDescriptor nested(Field field, int nestingLevel) {
 	}
 
 	/**
-	 * Creates a type descriptor for a nested type declared within the property.
+	 * Create a type descriptor for a nested type declared within the property.
 	 * <p>For example, if the property is a {@code List<String>} and the nesting
 	 * level is 1, the nested type descriptor will be {@code String.class}.
 	 * <p>If the property is a {@code List<List<String>>} and the nesting level
@@ -681,9 +682,9 @@ public static TypeDescriptor nested(Field field, int nestingLevel) {
 	 * is 1, the nested type descriptor will be String, derived from the map value.
 	 * <p>If the property is a {@code List<Map<Integer, String>>} and the nesting
 	 * level is 2, the nested type descriptor will be String, derived from the map value.
-	 * <p>Returns {@code null} if a nested type cannot be obtained because it was not declared.
-	 * For example, if the property is a {@code List<?>}, the nested type descriptor
-	 * returned will be {@code null}.
+	 * <p>Returns {@code null} if a nested type cannot be obtained because it was not
+	 * declared. For example, if the property is a {@code List<?>}, the nested type
+	 * descriptor returned will be {@code null}.
 	 * @param property the property
 	 * @param nestingLevel the nesting level of the collection/array element or
 	 * map key/value declaration within the property