title: Jenkinsfile Active Choice Parameter
body: <p>How can i use this dsl script in Multibranch Pipeline jenkinsfile(declerative)?</p>
  
  <pre><code>parameters {
          activeChoiceParam('States') {
              description('Select a state option')
              filterable()
              choiceType('SINGLE_SELECT')
              groovyScript {
                  script('["Sao Paulo", "Rio de Janeiro", "Parana:selected", "Acre"]')
                  fallbackScript('return ["ERROR"]')
              }
          }
          activeChoiceReactiveParam('Cities') {
              description('Active Choices Reactive parameter')
              filterable()
              choiceType('CHECKBOX')
              groovyScript {
                  script('''
  if (States.equals('Sao Paulo')) {
      return ['Barretos', 'Sao Paulo', 'Itu'];
  } else if (States.equals('Rio de Janeiro')) {
      return ['Rio de Janeiro', 'Mangaratiba']
  } else if (States.equals('Parana')) {
      return ['Curitiba', 'Ponta Grossa']
  } else if (States.equals('Acre')) {
      return ['Rio Branco', 'Acrelandia']
  } else {
      return ['Unknown state']
  }
                         ''')
                  fallbackScript('return ["Script error!"]')
              }
              referencedParameter('States')
          }
      }
  </code></pre>
  
  <p>When i use this script in jenkinsfile i get this error:</p>
  
  <p>WorkflowScript: 23: Build parameters definitions cannot have blocks @ line 23, column 5.
         activeChoiceParam('States') {
         ^</p>
  
  <p>WorkflowScript: 32: Build parameters definitions cannot have blocks @ line 32, column 9.
             activeChoiceReactiveParam('Cities') {
             ^</p>
  
  <p>2 errors</p>
  
  <pre><code>at org.codehaus.groovy.control.ErrorCollector.failIfErrors(ErrorCollector.java:310)
  at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:1085)
  at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:603)
  at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:581)
  at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:558)
  at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:298)
  at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:268)
  at groovy.lang.GroovyShell.parseClass(GroovyShell.java:688)
  at groovy.lang.GroovyShell.parse(GroovyShell.java:700)
  at org.jenkinsci.plugins.workflow.cps.CpsGroovyShell.doParse(CpsGroovyShell.java:131)
  at org.jenkinsci.plugins.workflow.cps.CpsGroovyShell.reparse(CpsGroovyShell.java:125)
  at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.parseScript(CpsFlowExecution.java:560)
  at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.start(CpsFlowExecution.java:521)
  at org.jenkinsci.plugins.workflow.job.WorkflowRun.run(WorkflowRun.java:325)
  at hudson.model.ResourceController.execute(ResourceController.java:97)
  at hudson.model.Executor.run(Executor.java:429)
  </code></pre>
  
  <p>Finished: FAILURE</p>