def getEnv() {
     return["Dev","Prod"] 
}
def getServerByEnvParam(env_param) {
    if (env_param.equals("Dev")){
        return["dev01","dev02"]
    }
    else if(env_param.equals("Prod")){
        return["prd001","prd02"]
    } else {
        return["unknown"]
    }
}
properties([
    parameters([
        [$class: 'ChoiceParameter', 
            choiceType: 'PT_SINGLE_SELECT', 
            description: 'Select Environment', 
            name: 'myEnv', 
            script: [
                $class: 'GroovyScript', 
                fallbackScript: [
                    classpath: [], 
                    sandbox: false, 
                    script: 
                        'return[\'myEnv Error\']'
                ], 
                script: [
                    classpath: [], 
                    sandbox: false, 
                    script: 
                        'return getEnv()'
                ]
            ]
        ], 
        [$class: 'CascadeChoiceParameter', 
            choiceType: 'PT_SINGLE_SELECT', 
            description: 'Select Server', 
            filterable: false, 
            name: 'myServer', 
            referencedParameters: 'myEnv', 
            script: [
                $class: 'GroovyScript', 
                fallbackScript: [
                    classpath: [], 
                    sandbox: false, 
                    script: 
                        'return[\'myServer Error\']'
                ], 
                script: [
                    classpath: [], 
                    sandbox: false, 
                    script: 
                        'return getServerByEnvParam(myEnv)'
                ]
            ]
        ]
    ])
])
pipeline {
    agent any    stages {
        stage('Init') {
            steps {
                script{
                    println getServerByEnvParam(myEnv)
                }
            }
        }
    }
}