@Override
        public void onNext(Object outputObject) {
            if (ClassUtils.isAssignable(Message.class, outputObject.getClass())) {
                getOutputChannel().send((Message) outputObject);
            } else {
                getOutputChannel().send(MessageBuilder.withPayload(outputObject).build());
            }
        }
Returns the input type of the stream that is to be processed
spring-xd-reactor/src/main/java/org/springframework/xd/reactor/AbstractReactorMessageHandler.java