code: public static void logException( Logger logger, Level logLevel, Throwable t ) {
  		logException( logger, logLevel, t, null );
  	}
docs: Logs an exception with the given logger and the given level.
  <p>
  Writing a stack trace may be time-consuming in some environments.
  To prevent useless computing, this method checks the current log level
  before trying to log anything.
  </p>
  
  @param logger the logger
  @param t an exception or a throwable
  @param logLevel the log level (see {@link Level})