code: private String getErrorMessage(final Throwable throwable, final Locale locale) {
  		String message;
  		if (!(throwable instanceof GeomajasException)) {
  			message = throwable.getMessage();
  		} else {
  			message = ((GeomajasException) throwable).getMessage(locale);
  		}
  		if (null == message || 0 == message.length()) {
  			message = throwable.getClass().getName();
  		}
  		return message;
  	}
docs: Get localized error message for a {@link Throwable}.
  
  @param throwable throwable to get message for
  @param locale locale to use for message
  @return exception message