title: Spring Cloud Stream message from/to JSON conversion configuration
body: <p>I am using Spring Cloud Stream, with RabbitMQ binder. It works great with <code>byte[]</code> payload and Java native serialization, but I need to work with JSON payload.</p>
  
  <p>Here's my processor class.</p>
  
  <pre><code>@EnableBinding(Processor.class)
  public class MessageProcessor {
      @ServiceActivator(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
      public OutputDto handleIncomingMessage(InputDto inputDto) {
          // Run some job.
          return new OutputDto();
      }
  }
  </code></pre>
  
  <p><code>InputDto</code> and <code>OutputDto</code> are POJOs with Jackson annotations.</p>
  
  <ul>
  <li>How do I configure JSON conversion strategy?</li>
  <li>How should message headers look like to be accepted and processed?</li>
  </ul>