AbstractHandlerMethodMapping adds type+method info to getMappingForMethod exceptions

Issue: SPR-14452
(cherry picked from commit 8ccd727)

Author: jhoeller

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java

@@ -231,7 +231,13 @@ protected void detectHandlerMethods(final Object handler) {
 				new MethodIntrospector.MetadataLookup<T>() {
 					@Override
 					public T inspect(Method method) {
-						return getMappingForMethod(method, userType);
+						try {
+							return getMappingForMethod(method, userType);
+						}
+						catch (Throwable ex) {
+							throw new IllegalStateException("Invalid mapping on handler class [" +
+									userType.getName() + "]: " + method, ex);
+						}
 					}
 				});