properties([
 parameters([ 
  [$class: 'ChoiceParameter',
   choiceType: 'PT_SINGLE_SELECT',
   description: 'Choose env',
   name: 'ENVIRONMENT',
   sandbox: true,
   script: 'return["none","dev","int","prod"]' ] 
script: [ 
   $class: 'GroovyScript',
    fallbackScript: [
 classpath: [], 
   sandbox: true, 
   script: 'return[\'Environment not found\']' ], 
   script: [ classpath: [], ] ], 
    [$class: 'CascadeChoiceParameter', 
     choiceType: 'PT_SINGLE_SELECT', 
     description: 'Choose snapshot for selected env', 
     name: 'SNAPSHOT', 
     referencedParameters: 'ENVIRONMENT', 
     script: [ $class: 'GroovyScript', 
     fallbackScript: 
     [ classpath: [], 
     sandbox: true, 
      script: 'return["FAILED"]' ], 
      script: [ classpath: [], 
      sandbox: true, 
      script: """ 
           def snapshotsL = "git tag -l --sort=v:refname \"v*-SNAPSHOT\" | tail -5" 
            return [snapshotsL] """ ] ] ] ]) ])


Above script always returns FAILED. Either I am not sure, how to capture the git command out and return or this functionality isn't available.

Please assist.