code: private static void printEnvVariables() {
      System.out.println("Environment Variables: ");
      Map<String,String> map = System.getenv();
      Set<Entry<String, String>> entrySet = map.entrySet();
      for(Entry<String, String> entry : entrySet) {
        System.out.println(entry.getKey() + " = " + entry.getValue());
      }
    }
docs: prints all environment variables for this process