title: nifi: how to change value of json?
body: <p>i have processor InvokeHTTP which gives json result.
  for instance:</p>
  
  <pre><code>{
    "revision" : {
      "clientId" : "dc572274-4b71-11b6-e415-b91e391bcf4d",
      "version" : 7
    },
    "id" : "dc572260-4b71-11b6-0371-f73573ab44fe",
    "uri" : "http://x.x.x.x:9090/nifi-api/processors/dc572260-4b71-0371-73ab44fe",
    "position" : {
      "x" : -1021.9568138214972,
      "y" : 333.2029958718132
    }
  }
  </code></pre>
  
  <p>i want to change the value of version dynamically for each incoming response of InvokeHTTP.
  how to achieve this?</p>