Honor generic type information in BeanUtils.copyProperties()

spring-beans/src/main/java/org/springframework/beans/BeanUtils.java

@@ -44,6 +44,7 @@
 
 import org.springframework.core.KotlinDetector;
 import org.springframework.core.MethodParameter;
+import org.springframework.core.ResolvableType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -711,21 +712,24 @@ private static void copyProperties(Object source, Object target, @Nullable Class
 				PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
 				if (sourcePd != null) {
 					Method readMethod = sourcePd.getReadMethod();
-					if (readMethod != null &&
-							ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {
-						try {
-							if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
-								readMethod.setAccessible(true);
+					if (readMethod != null) {
+						ResolvableType sourceResolvableType = ResolvableType.forMethodReturnType(readMethod);
+						ResolvableType targetResolvableType = ResolvableType.forMethodParameter(writeMethod, 0);
+						if (targetResolvableType.isAssignableFrom(sourceResolvableType)) {
+							try {
+								if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
+									readMethod.setAccessible(true);
+								}
+								Object value = readMethod.invoke(source);
+								if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
+									writeMethod.setAccessible(true);
+								}
+								writeMethod.invoke(target, value);
 							}
-							Object value = readMethod.invoke(source);
-							if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
-								writeMethod.setAccessible(true);
+							catch (Throwable ex) {
+								throw new FatalBeanException(
+										"Could not copy property '" + targetPd.getName() + "' from source to target", ex);
 							}
-							writeMethod.invoke(target, value);
-						}
-						catch (Throwable ex) {
-							throw new FatalBeanException(
-									"Could not copy property '" + targetPd.getName() + "' from source to target", ex);
 						}
 					}
 				}

spring-beans/src/test/java/org/springframework/beans/BeanUtilsTests.java

@@ -24,6 +24,7 @@
 import java.net.URL;
 import java.time.DayOfWeek;
 import java.time.LocalDateTime;
+import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
@@ -331,6 +332,60 @@ private void assertSignatureEquals(Method desiredMethod, String signature) {
 		assertThat(BeanUtils.resolveSignature(signature, MethodSignatureBean.class)).isEqualTo(desiredMethod);
 	}
 
+	@Test
+	void copyPropertiesWithGenericTypes() {
+		ListComponentA a = new ListComponentA();
+		a.getList().add(42);
+		ListComponentB b = new ListComponentB();
+		ListComponentC c = new ListComponentC();
+
+		BeanUtils.copyProperties(a, b);
+		assertThat(a.getList()).containsOnly(42);
+		assertThat(b.getList()).containsOnly(42);
+
+		BeanUtils.copyProperties(a, c);
+		assertThat(c.getList()).isEmpty();
+	}
+
+	static class ListComponentA {
+
+		private List<Integer> list = new ArrayList<>();
+
+		public List<Integer> getList() {
+			return list;
+		}
+
+		public void setList(List<Integer> list) {
+			this.list = list;
+		}
+	}
+
+	static class ListComponentB {
+
+		private List<Integer> list = new ArrayList<>();
+
+		public List<Integer> getList() {
+			return list;
+		}
+
+		public void setList(List<Integer> list) {
+			this.list = list;
+		}
+	}
+
+	static class ListComponentC {
+
+		private List<Long> list = new ArrayList<>();
+
+		public List<Long> getList() {
+			return list;
+		}
+
+		public void setList(List<Long> list) {
+			this.list = list;
+		}
+	}
+
 
 	@SuppressWarnings("unused")
 	private static class NameAndSpecialProperty {