Narrowing the return type causes the following exception when running 1.3.2 against the new client...

    Exception in thread "SimpleAsyncTaskExecutor-1" java.lang.NoSuchMethodError: com.rabbitmq.client.ShutdownSignalException.getReason()Ljava/lang/Object;

This is because the compiler can't ensure the caller doesn't expect some object other than method.

This was the original problem found by the reporter in the forum post.