code: public String getPid() {
          String arg = extraArgs.size() > 0 ? extraArgs.get(0) : null;
          return arg != null && arg.matches("^\\d+$") ? arg : null;
      }
docs: Process id as given as argument (if any). If a pattern for matching the process name is used, this
  method returns null.
  
  @return process id or null