Consider generic information on @Bean method for bind

Fixes gh-11931

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationBeanFactoryMetadata.java

@@ -82,6 +82,9 @@ public class ConfigurationBeanFactoryMetadata implements BeanFactoryPostProcesso
 		FactoryMetadata metadata = this.beansFactoryMetadata.get(beanName);
 		Class<?> factoryType = this.beanFactory.getType(metadata.getBean());
 		String factoryMethod = metadata.getMethod();
+		if (ClassUtils.isCglibProxyClass(factoryType)) {
+			factoryType = factoryType.getSuperclass();
+		}
 		ReflectionUtils.doWithMethods(factoryType, (method) -> {
 			if (method.getName().equals(factoryMethod)) {
 				found.compareAndSet(null, method);

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBinder.java

@@ -26,6 +26,7 @@ import org.springframework.boot.context.properties.bind.validation.ValidationBin
 import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
 import org.springframework.boot.context.properties.source.UnboundElementsSourceFilter;
+import org.springframework.core.ResolvableType;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.env.PropertySource;
 import org.springframework.util.Assert;
@@ -69,12 +70,13 @@ class ConfigurationPropertiesBinder {
 	 * specified {@code annotation}.
 	 * @param target the target to bind the configuration property sources to
 	 * @param annotation the binding configuration
+	 * @param targetType the resolvable type for the target
 	 * @throws ConfigurationPropertiesBindingException if the binding failed
 	 */
-	void bind(Object target, ConfigurationProperties annotation) {
+	void bind(Object target, ConfigurationProperties annotation, ResolvableType targetType) {
 		Validator validator = determineValidator(target);
 		BindHandler handler = getBindHandler(annotation, validator);
-		Bindable<?> bindable = Bindable.ofInstance(target);
+		Bindable<?> bindable = Bindable.of(targetType).withExistingValue(target);
 		try {
 			this.binder.bind(annotation.prefix(), bindable, handler);
 		}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties;
 
+import java.lang.reflect.Method;
 import java.util.Map;
 
 import org.apache.commons.logging.Log;
@@ -34,6 +35,7 @@ import org.springframework.context.EnvironmentAware;
 import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
 import org.springframework.core.Ordered;
 import org.springframework.core.PriorityOrdered;
+import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
@@ -164,7 +166,12 @@ public class ConfigurationPropertiesBindingPostProcessor
 		ConfigurationProperties annotation = getAnnotation(bean, beanName);
 		if (annotation != null) {
 			try {
-				getBinder().bind(bean, annotation);
+				ResolvableType type = ResolvableType.forClass(bean.getClass());
+				Method factoryMethod = this.beans.findFactoryMethod(beanName);
+				if (factoryMethod != null) {
+					type = ResolvableType.forMethodReturnType(factoryMethod);
+				}
+				getBinder().bind(bean, annotation, type);
 			}
 			catch (ConfigurationPropertiesBindingException ex) {
 				throw new BeanCreationException(beanName, ex.getMessage(), ex.getCause());

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java

@@ -28,6 +28,7 @@ import java.util.function.Supplier;
 import org.springframework.beans.BeanUtils;
 import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
 import org.springframework.boot.context.properties.source.ConfigurationPropertyState;
+import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
 
 /**
@@ -91,9 +92,12 @@ class JavaBeanBinder implements BeanBinder {
 
 		private final Class<?> type;
 
+		private final ResolvableType resolvableType;
+
 		private final Map<String, BeanProperty> properties = new LinkedHashMap<>();
 
-		Bean(Class<?> type) {
+		Bean(ResolvableType resolvableType, Class<?> type) {
+			this.resolvableType = resolvableType;
 			this.type = type;
 			putProperties(type);
 		}
@@ -123,17 +127,17 @@ class JavaBeanBinder implements BeanBinder {
 			int parameterCount = method.getParameterCount();
 			if (name.startsWith("get") && parameterCount == 0) {
 				name = Introspector.decapitalize(name.substring(3));
-				this.properties.computeIfAbsent(name, BeanProperty::new)
+				this.properties.computeIfAbsent(name, n -> new BeanProperty(n, this.resolvableType))
 						.addGetter(method);
 			}
 			else if (name.startsWith("is") && parameterCount == 0) {
 				name = Introspector.decapitalize(name.substring(2));
-				this.properties.computeIfAbsent(name, BeanProperty::new)
+				this.properties.computeIfAbsent(name, n -> new BeanProperty(n, this.resolvableType))
 						.addGetter(method);
 			}
 			else if (name.startsWith("set") && parameterCount == 1) {
 				name = Introspector.decapitalize(name.substring(3));
-				this.properties.computeIfAbsent(name, BeanProperty::new)
+				this.properties.computeIfAbsent(name, n -> new BeanProperty(n, this.resolvableType))
 						.addSetter(method);
 			}
 		}
@@ -169,7 +173,7 @@ class JavaBeanBinder implements BeanBinder {
 
 		@SuppressWarnings("unchecked")
 		public static <T> Bean<T> get(Bindable<T> bindable, boolean canCallGetValue) {
-			Class<?> type = bindable.getType().resolve();
+			Class<?> type = bindable.getType().resolve(Object.class);
 			Supplier<T> value = bindable.getValue();
 			T instance = null;
 			if (canCallGetValue && value != null) {
@@ -181,7 +185,7 @@ class JavaBeanBinder implements BeanBinder {
 			}
 			Bean<?> bean = Bean.cached;
 			if (bean == null || !type.equals(bean.getType())) {
-				bean = new Bean<>(type);
+				bean = new Bean<>(bindable.getType(), type);
 				cached = bean;
 			}
 			return (Bean<T>) bean;
@@ -229,14 +233,17 @@ class JavaBeanBinder implements BeanBinder {
 
 		private final String name;
 
+		private final ResolvableType declaringClassType;
+
 		private Method getter;
 
 		private Method setter;
 
 		private Field field;
 
-		BeanProperty(String name) {
+		BeanProperty(String name, ResolvableType declaringClassType) {
 			this.name = BeanPropertyName.toDashedForm(name);
+			this.declaringClassType = declaringClassType;
 		}
 
 		public void addGetter(Method getter) {
@@ -263,9 +270,11 @@ class JavaBeanBinder implements BeanBinder {
 
 		public ResolvableType getType() {
 			if (this.setter != null) {
-				return ResolvableType.forMethodParameter(this.setter, 0);
+				MethodParameter methodParameter = new MethodParameter(this.setter, 0);
+				return ResolvableType.forMethodParameter(methodParameter, this.declaringClassType);
 			}
-			return ResolvableType.forMethodReturnType(this.getter);
+			MethodParameter methodParameter = new MethodParameter(this.getter, -1);
+			return ResolvableType.forMethodParameter(methodParameter, this.declaringClassType);
 		}
 
 		public Annotation[] getAnnotations() {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBinderBuilderTests.java

@@ -25,6 +25,7 @@ import org.junit.Test;
 import org.springframework.boot.context.properties.bind.validation.BindValidationException;
 import org.springframework.boot.context.properties.bind.validation.ValidationErrors;
 import org.springframework.context.support.StaticApplicationContext;
+import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.mock.env.MockEnvironment;
@@ -128,7 +129,7 @@ public class ConfigurationPropertiesBinderBuilderTests {
 
 	private void bind(ConfigurationPropertiesBinder binder, Object target) {
 		binder.bind(target, AnnotationUtils.findAnnotation(target.getClass(),
-				ConfigurationProperties.class));
+				ConfigurationProperties.class), ResolvableType.forType(target.getClass()));
 	}
 
 	@ConfigurationProperties(prefix = "test")

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBinderTests.java

@@ -25,6 +25,7 @@ import org.junit.Test;
 import org.springframework.boot.context.properties.bind.BindException;
 import org.springframework.boot.context.properties.bind.validation.BindValidationException;
 import org.springframework.boot.context.properties.bind.validation.ValidationErrors;
+import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.MutablePropertySources;
@@ -269,7 +270,7 @@ public class ConfigurationPropertiesBinderTests {
 
 	private void bind(ConfigurationPropertiesBinder binder, Object target) {
 		binder.bind(target, AnnotationUtils.findAnnotation(target.getClass(),
-				ConfigurationProperties.class));
+				ConfigurationProperties.class), ResolvableType.forType(target.getClass()));
 	}
 
 	@ConfigurationProperties(value = "person", ignoreUnknownFields = false)

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessorTests.java

@@ -287,6 +287,20 @@ public class ConfigurationPropertiesBindingPostProcessorTests {
 		assertThat(foo.getFoos().get("1")).isNotNull();
 	}
 
+	@Test
+	public void bindToBeanWithGenerics() {
+		this.context = new AnnotationConfigApplicationContext();
+		MutablePropertySources sources = this.context.getEnvironment()
+				.getPropertySources();
+		Map<String, Object> source = new LinkedHashMap<>();
+		source.put("foo.bar", "hello");
+		sources.addFirst(new MapPropertySource("test-source", source));
+		this.context.register(GenericConfiguration.class);
+		this.context.refresh();
+		AGenericClass foo = this.context.getBean(AGenericClass.class);
+		assertThat(foo.getBar()).isNotNull();
+	}
+
 	private void prepareConverterContext(Class<?>... config) {
 		this.context = new AnnotationConfigApplicationContext();
 		MutablePropertySources sources = this.context.getEnvironment()
@@ -645,4 +659,30 @@ public class ConfigurationPropertiesBindingPostProcessorTests {
 
 	}
 
+	@Configuration
+	@EnableConfigurationProperties
+	static class GenericConfiguration {
+
+		@Bean
+		@ConfigurationProperties("foo")
+		public AGenericClass<String> aBeanToBind() {
+			return new AGenericClass<>();
+		}
+
+	}
+
+	static class AGenericClass<T> {
+
+		private T bar;
+
+		public T getBar() {
+			return this.bar;
+		}
+
+		public void setBar(T bar) {
+			this.bar = bar;
+		}
+
+	}
+
 }