I am working on something quite similar but I don't manage to make it work ... I succeed in getting messages from rabbitmq, that means my cMessagingEndpoint component is well configured. But then i need to extract all informations contained in my message (Headers and Payload). I have built the same route and job as you but i still don't know how to configure these 3 components : cSetHeader, cProcessor, cExtractJsonFields.
You can find attached my current work.