title: Groovy - How to check if a json key exists
body: <p>I'm creating a REST Mock that will receive as input a JSON request:</p>
  
  <pre><code>{  
       "infoSimIn":{
          "idenficationSim":[ 
              { 
                  "imsi":123456789012345
              }
            ]
         } 
  }
  </code></pre>
  
  <p>How can i check if my JSON contains  <code>imsi</code> Key, before returning the appropriate response ?</p>
  
  <p>Thanks u..</p>