code: public void debug(String format, Object... args)
      {
          if (logger.isLoggable(FINE)) {
              String message;
              try {
                  message = format(format, args);
              }
              catch (IllegalFormatException e) {
                  logger.log(SEVERE, illegalFormatMessageFor("DEBUG", format, args), e);
                  message = rawMessageFor(format, args);
              }
              logger.fine(message);
          }
      }
docs: Logs a message at DEBUG level.
  <p>
  Usage example:
  <pre>
  logger.debug("value is %s (%d ms)", value, time);
  </pre>
  If the format string is invalid or the arguments are insufficient, an error will be logged and execution
  will continue.
  
  @param format a format string compatible with String.format()
  @param args arguments for the format string