PayloadArgumentResolver's MessageConversionException includes original payload type

Issue: SPR-14394

Author: jhoeller

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/PayloadArgumentResolver.java

@@ -106,7 +106,8 @@ public Object resolveArgument(MethodParameter parameter, Message<?> message) thr
 		}
 
 		Class<?> targetClass = parameter.getParameterType();
-		if (ClassUtils.isAssignable(targetClass, payload.getClass())) {
+		Class<?> payloadClass = payload.getClass();
+		if (ClassUtils.isAssignable(targetClass, payloadClass)) {
 			validate(message, parameter, payload);
 			return payload;
 		}
@@ -119,8 +120,8 @@ public Object resolveArgument(MethodParameter parameter, Message<?> message) thr
 				payload = this.converter.fromMessage(message, targetClass);
 			}
 			if (payload == null) {
-				throw new MessageConversionException(message,
-						"No converter found to convert to " + targetClass + ", message=" + message);
+				throw new MessageConversionException(message, "Cannot convert from [" +
+						payloadClass.getName() + "] to [" + targetClass.getName() + "] for " + message);
 			}
 			validate(message, parameter, payload);
 			return payload;

spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/PayloadArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -132,7 +132,7 @@ public void resolveNonConvertibleParam() throws Exception {
 		Message<?> notEmptyMessage = MessageBuilder.withPayload(123).build();
 
 		thrown.expect(MessageConversionException.class);
-		thrown.expectMessage("No converter found");
+		thrown.expectMessage("Cannot convert");
 		this.resolver.resolveArgument(this.paramAnnotatedRequired, notEmptyMessage);
 	}