title: using jolt to transform empty field
body: <p>my json looks like this</p>
  
  <pre><code>{  
      "group":{  
          "personnel":[  
              {  
                  "member":{  
                      "id":"1",
                      "name":"John"
                  }
              },
              {  
                  "member":{  
                      "id":"2",
                      "name":"Doe"
                  }
              }
          ]
      }
  }
  </code></pre>
  
  <p>and the expected output for this is</p>
  
  <pre><code>[  
      {  
          "id":"1",
          "name":"John"
      },
      {  
          "id":"2",
          "name":"Doe"
      }
  ]
  </code></pre>
  
  <p>but, there's also some time when the json is empty like so:</p>
  
  <pre><code>{}
  </code></pre>
  
  <p>for this, I want the output to be</p>
  
  <pre><code>[]
  </code></pre>
  
  <p>my spec looks like this</p>
  
  <pre><code>"spec":{  
      "group":{  
          "personnel":{  
              "*":{  
                  "*":"[]"
              }
          }
      }
  }
  </code></pre>
  
  <p>but this doesnt work on the second case where json is empty, it'll just return null. do I need to add anything?</p>