How about concatenate the Integers that you made into a String and then return the String back to your program.
As an example,
@Keyword
def String randomSSN() {
Random rand = new Random();
// Generate random SSN.
int ssn1ssn = rand.nextInt(600)+100;
int ssn2ssn = rand.nextInt(89)+10;
int ssn3ssn = rand.nextInt(8999)+1000;
// return random SSN
return "${ssn1ssn.toString()}-${ssn2ssn.toString()}-${ssn3ssn.toString()}";
}
And then, like @Dave_Evers has:
Test case:
def SSN = CustomKeywords.'App.appFunctions.randomSSN'();
System.out.println(SSN);