title: RabbitMQ REST HTTP JSON payload
body: <p>I am trying to use RabbitMQ HTTP REST client to publish messages into the queue. I am using the following url and request</p>
  
  <p><a href="http://xxxx/api/exchanges/xxxx/exc.notif/publish" rel="noreferrer">http://xxxx/api/exchanges/xxxx/exc.notif/publish</a></p>
  
  <pre><code>{
   "routing_key":"routing.key",
    "payload":{
  
    },
   "payload_encoding":"string",
   "properties":{
     "headers":{
       "notif_d":"TEST",
       "notif_k": ["example1", "example2"],
       "userModTime":"timestamp"
     }
   }
  }
  </code></pre>
  
  <p>And getting back from the rabbit the following response:</p>
  
  <pre><code>{"error":"bad_request","reason":"payload_not_string"}
  </code></pre>
  
  <p>I have just one header set:</p>
  
  <pre><code>Content-Type:application/json
  </code></pre>
  
  <p>I was trying to set the</p>
  
  <pre><code>"payload_encoding":"base64",
  </code></pre>
  
  <p>but it didn't help. I am new to rabbit any response is welcome.  </p>