public static String formatStringOrNull(String formatString, Object... args) {
    for (Object o : args) {
      if (o == null) {
        return null;
      }
    }
    return String.format(formatString, args);
  }
Return the formatted string unless one of the args is null in which case null is returned

@param formatString the standard Java format string
@param args objects to put in the format string
@return formatted String or null
app/com/linkedin/drelephant/util/Utils.java