docs: @Check
  	public void checkDefaultValueFieldReference(SarlFormalParameter param) {
  		final XExpression defaultValue = param.getDefaultValue();
  		if (defaultValue != null) {
  			final Iterator<XFeatureCall> iter;
  			if (defaultValue instanceof XFeatureCall) {
  				iter = Iterators.singletonIterator((XFeatureCall) defaultValue);
  			} else {
  				iter = Iterators.filter(defaultValue.eAllContents(), XFeatureCall.class);
  			}
  			while (iter.hasNext()) {
  				final XFeatureCall call = iter.next();
  				final JvmIdentifiableElement feature = call.getFeature();
  				String invalidFieldName = null;
  				if (feature instanceof XtendField) {
  					final XtendField field = (XtendField) feature;
  					if (!field.isFinal()) {
  						invalidFieldName = field.getName();
  					}
  				} else if (feature instanceof JvmField) {
  					final JvmField field = (JvmField) feature;
  					if (!field.isFinal()) {
  						invalidFieldName = field.getSimpleName();
  					}
  				}
  				if (invalidFieldName != null) {
  					error(MessageFormat.format(
  							Messages.SARLValidator_19,
  							invalidFieldName),
  							call,
  							XbasePackage.Literals.XABSTRACT_FEATURE_CALL__FEATURE,
  							ValidationMessageAcceptor.INSIGNIFICANT_INDEX,
  							FORBIDDEN_REFERENCE);
  				}
  			}
  		}
  	}