Here you can find the source of randomId()
public static String randomId()
//package com.java2s; //License from project: Apache License import java.util.*; public class Main { /**/*from w w w. j av a 2 s. c o m*/ * Create and return an ID that's (virtually) guaranteed not to name a real object on a * GA4GH server. It uses {@link UUID#randomUUID()} to do it. * This is identical to {@link #randomName()} but for the name. * @return an ID that's (virtually) guaranteed not to name a real object */ public static String randomId() { return UUID.randomUUID().toString(); } }