title: Jenkinsfile class CascadeChoiceParameter return my array as a string
body: <p>I'm trying to use the CascadeChoiceParameter to dynamically mount my parameters form, using commands to create my list of options:</p>
  
  <pre><code>                    choiceType: 'PT_SINGLE_SELECT', 
                      description: 'Informations about the application on kubernetes', 
                      name: 'deployments', 
                      omitValueField: false, 
                      randomName: 'choice-parameter-5633384460832175', 
                      referencedParameters: 'namespaces', 
                      script: [
                          $class: 'GroovyScript', 
                          script: [
                              classpath: [],
                              sandbox: true,
                              script: """
                                  if (namespaces.equals("Select")){
                                      return["Nothing to do - Select your deployment"]
                                  } else {
                                      def kubecmd = "kubectl get deploy --kubeconfig=${kubefileHlg} -o jsonpath={.items[*].metadata.name} -n " + namespaces
                                      return [kubecmd.execute().in.text.split()]
  
                                  }
                              """
  
                          ]
  </code></pre>
  
  <p>The form parameter on Jenkins shows me this - a single option with all values comma separated:</p>
  
  <p><img src="https://i.stack.imgur.com/XmOoq.png" alt="Here the image"></p>
  
  <p>Do you have any idea how can I mount these options as a real list on it?</p>