title: Nifi jolt spec to flatten array
body: <p>I have json input with array:</p>
  
  <pre><code>{
      "id": 3,
      "name": "ROOT",
      "mylist": [{
          "id": 10,
          "info": "hello"
          },
          {
          "id": 11,
          "info": "world"
          }
      ]
  }
  </code></pre>
  
  <p>That i would like to transform into "flat" json like the following:</p>
  
  <pre><code>{
      "id": 3,
      "name": "Root",
      "mylist[0].id": 10,
      "mylist[0].info": "hello",
      "mylist[1].id": 11,
      "mylist[1].info": "world"    
  }
  </code></pre>
  
  <p>How can i achieve that with JoltTransformJSON spec?</p>