try

Jenkinsfile

@@ -1,23 +1,28 @@
 properties([parameters([[$class: 'DynamicReferenceParameter', choiceType: 'ET_FORMATTED_HTML', name: 'General', omitValueField: false, randomName: 'choice-parameter-517572555514769', referencedParameters: '', script: [$class: 'GroovyScript', fallbackScript: [classpath: [], oldScript: '', sandbox: false, script: ''], script: [classpath: [], oldScript: '', sandbox: true, 
 script: '''
-def generator = { String alphabet, int n ->
-  new Random().with {
-    (1..n).collect { alphabet[ nextInt( alphabet.length() ) ] }.join()
-  }
-}
-randomValue = generator( (('A'..'Z')+('0'..'9')+('a'..'z')).join(), 9 )
 
-vappHtml = """
+try {
+
+def demoID = new Random().with {(1..15).collect {(('a'..'z')).join('')[ nextInt((('a'..'z')).join('').length())]}.join('')}
+
+paramHtml = """
+<script>
+  
+     Q("p").text("Hello world!");
+   
+</script>
+
 <ul style="list-style-type: none">
     <li style="padding: 5px">
-    <label>${randomValue}</label>
-    <input type="text" class="jenkins-input" name="value">
+     <label>Demo Name (Optional)</label>
+     <input type="text" class="jenkins-input" size="20"  name="value"><a>-nttdata</a>
   </li>
 </ul>
 <p>Demo Url will be: </p>
 """
+}catch(e){ return [e.toString()] }
 
-return vappHtml
+return paramHtml
 
 ''']]]])])