code: private Throwable throwable(final LoggingEvent loggingEvent) {
  		ThrowableInformation throwableInfo = loggingEvent.getThrowableInformation();
  		if (throwableInfo != null)
  			return throwableInfo.getThrowable();
  		
  		Object message = loggingEvent.getMessage();
  		if (message instanceof Throwable)
  			return (Throwable) message;
  		
  		return null;
  	}
docs: Get the throwable information contained in a {@link LoggingEvent}.
  Returns the Throwable passed to the logger or the message if it's a
  Throwable.
  @param loggingEvent
  @return The Throwable contained in the {@link LoggingEvent} or null if there is none.