title: how to customize grails restful controller error response
body: <p>How do we customize grails <strong>RestfulController</strong> error response? For example one of my restful controller returning following response by default on error while trying to save object.</p>
  
  <pre><code>{
    "errors": 
    [
      {
         "object": "com.test.Task",
         "field": "description",
         "rejected-value": null,
         "message": "Property [description] of class [class com.test.Task] cannot be null"
      }
    ]
  }
  </code></pre>
  
  <p>I would like to customize the response as bellow.</p>
  
  <pre><code>{
     "errors" : 
      {
         "message": "Property [description] of class [class com.test.Task] cannot be" 
      },
      {
         "message": "This is going to be any 2nd message"
      },
      .....
  }
  </code></pre>