Groovy add()

class Example {
   static void main(String[] args) {
      def testCaseTag = "@a or @b"
     
    def tag = "'(" + testCaseTag + ")'"
      
      testCaseTag = './gradlew -Dcucumber.options="--tags '+tag+'" test --refresh-dependencies'
     
      println(testCaseTag)
   } 
}