title: Grails 2.5.3 controller params is read-only on tests but not on run-app
body: <p>In a controller action I have a code like this:</p>
  
  <pre><code>if (!format)
  {
      params.format = 'json'
  }
  </code></pre>
  
  <p>This works perfectly on run-app</p>
  
  <p>But testing the same code from an integration test, I get:</p>
  
  <pre><code>groovy.lang.ReadOnlyPropertyException: Cannot set readonly property: params for class: com.cabolabs.ehrserver.api.RestController
  </code></pre>
  
  <p>Any ideas of what is wrong here?</p>
  
  <p>Thanks!</p>