docs: protected void error(String message, EObject source, EStructuralFeature feature) {
  		getContext().getMessageAcceptor().acceptError(
  				MessageFormat.format(getErrorMessageFormat(), message),
  				source,
  				feature,
  				ValidationMessageAcceptor.INSIGNIFICANT_INDEX,
  				IssueCodes.INVALID_EXTRA_LANGUAGE_GENERATION);
  	}