@Override
  public final PsiReference @NotNull [] getReferencesByElement(@NotNull PsiElement element, @NotNull ProcessingContext context) {
    final XmlAttributeValue xmlAttrVal = (XmlAttributeValue)element;
    final PsiFile containingFile = xmlAttrVal.getContainingFile();
    if (!JavaFxFileTypeFactory.isFxml(containingFile)) return PsiReference.EMPTY_ARRAY;

    final PsiClass controllerClass = JavaFxPsiUtil.getControllerClass(containingFile);
    return controllerClass != null ? getReferencesByElement(controllerClass, xmlAttrVal, context) 
                                   : new PsiReference[] {new PsiReferenceBase.Immediate<>(xmlAttrVal, xmlAttrVal)};
  }
@Override
  public final PsiReference @NotNull [] getReferencesByElement(@NotNull PsiElement element, @NotNull ProcessingContext context)