@ExceptionHandler resolves nested exceptions

See gh-23380

spring-web/src/main/java/org/springframework/web/method/annotation/ExceptionHandlerMethodResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -134,7 +134,7 @@ public class ExceptionHandlerMethodResolver {
 		if (method == null) {
 			Throwable cause = exception.getCause();
 			if (cause != null) {
-				method = resolveMethodByExceptionType(cause.getClass());
+				method = resolveMethodByThrowable(cause);
 			}
 		}
 		return method;

spring-web/src/test/java/org/springframework/web/method/annotation/ExceptionHandlerMethodResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -78,6 +78,18 @@ public class ExceptionHandlerMethodResolverTests {
 		assertThat(resolver.resolveMethod(exception)).as("2nd lookup from cache").isNull();
 	}
 
+	@Test
+	public void resolveMethodExceptionCause() {
+		ExceptionHandlerMethodResolver resolver = new ExceptionHandlerMethodResolver(ExceptionController.class);
+
+		SocketException bindException = new BindException();
+		bindException.initCause(new FileNotFoundException());
+
+		Exception exception = new Exception(new Exception(new Exception(bindException)));
+
+		assertThat(resolver.resolveMethod(exception).getName()).isEqualTo("handleSocketException");
+	}
+
 	@Test
 	public void resolveMethodInherited() {
 		ExceptionHandlerMethodResolver resolver = new ExceptionHandlerMethodResolver(InheritedController.class);