@Override
  public void visitXmlAttributeValue(XmlAttributeValue value) {
    final PsiElement parent = value.getParent();
    if (!(parent instanceof XmlAttribute)) {
      checkReferences(value);
      return;
    }

    XmlAttribute attribute = (XmlAttribute) parent;

    XmlTag tag = attribute.getParent();

    XmlElementDescriptor elementDescriptor = tag.getDescriptor();
    XmlAttributeDescriptor attributeDescriptor =
        elementDescriptor != null ? elementDescriptor.getAttributeDescriptor(attribute) : null;

    if (attributeDescriptor != null && !skipValidation(value)) {
      String error = attributeDescriptor.validateValue(value, attribute.getValue());

      if (error != null) {
        addToResults(HighlightInfo.createHighlightInfo(getTagProblemInfoType(tag), value, error));
        return;
      }
    }

    checkReferences(value);
  }
 @Override
 public void invoke(@NotNull Project project, Editor editor, @NotNull PsiElement element)
     throws IncorrectOperationException {
   if (!FileModificationService.getInstance().preparePsiElementsForWrite(element)) return;
   final XmlAttribute attr = (XmlAttribute) element.getParent();
   final String name = attr.getName();
   final XmlAttributeDescriptor descriptor = attr.getDescriptor();
   LOG.assertTrue(descriptor != null);
   String value = attr.getValue();
   final PsiElement declaration = descriptor.getDeclaration();
   if (declaration instanceof PsiField) {
     final PsiType fieldType = ((PsiField) declaration).getType();
     final PsiType itemType =
         JavaGenericsUtil.getCollectionItemType(fieldType, declaration.getResolveScope());
     if (itemType != null) {
       final String typeNode = itemType.getPresentableText();
       JavaFxPsiUtil.insertImportWhenNeeded(
           (XmlFile) attr.getContainingFile(), typeNode, itemType.getCanonicalText());
       final String[] vals = value.split(",");
       value =
           StringUtil.join(
               vals,
               new Function<String, String>() {
                 @Override
                 public String fun(String s) {
                   return "<"
                       + typeNode
                       + " "
                       + FxmlConstants.FX_VALUE
                       + "=\""
                       + s.trim()
                       + "\"/>";
                 }
               },
               "\n");
     }
   }
   final XmlTag childTag =
       XmlElementFactory.getInstance(project)
           .createTagFromText("<" + name + ">" + value + "</" + name + ">");
   attr.getParent().add(childTag);
   attr.delete();
 }
 @Override
 public void annotate(@NotNull final PsiElement element, @NotNull AnnotationHolder holder) {
   final PsiFile containingFile = element.getContainingFile();
   if (!JavaFxFileTypeFactory.isFxml(containingFile)) return;
   if (element instanceof XmlAttributeValue) {
     final String value = ((XmlAttributeValue) element).getValue();
     if (!JavaFxPsiUtil.isExpressionBinding(value)
         && !JavaFxPsiUtil.isIncorrectExpressionBinding(value)) {
       final PsiReference[] references = element.getReferences();
       for (PsiReference reference : references) {
         if (reference instanceof JavaFxColorReference) {
           attachColorIcon(element, holder, StringUtil.unquoteString(element.getText()));
           continue;
         }
         final PsiElement resolve = reference.resolve();
         if (resolve instanceof PsiMember) {
           if (!JavaFxPsiUtil.isVisibleInFxml((PsiMember) resolve)) {
             final String symbolPresentation =
                 "'" + SymbolPresentationUtil.getSymbolPresentableText(resolve) + "'";
             final Annotation annotation =
                 holder.createErrorAnnotation(
                     element,
                     symbolPresentation
                         + (resolve instanceof PsiClass
                             ? " should be public"
                             : " should be public or annotated with @FXML"));
             if (!(resolve instanceof PsiClass)) {
               annotation.registerUniversalFix(
                   new AddAnnotationFix(
                       JavaFxCommonNames.JAVAFX_FXML_ANNOTATION,
                       (PsiMember) resolve,
                       ArrayUtil.EMPTY_STRING_ARRAY),
                   null,
                   null);
             }
           }
         }
       }
     }
   } else if (element instanceof XmlAttribute) {
     final XmlAttribute attribute = (XmlAttribute) element;
     final String attributeName = attribute.getName();
     if (!FxmlConstants.FX_BUILT_IN_ATTRIBUTES.contains(attributeName)
         && !attribute.isNamespaceDeclaration()
         && JavaFxPsiUtil.isReadOnly(attributeName, attribute.getParent())) {
       holder.createErrorAnnotation(
           element.getNavigationElement(), "Property '" + attributeName + "' is read-only");
     }
     if (FxmlConstants.SOURCE.equals(attributeName)) {
       final XmlAttributeValue valueElement = attribute.getValueElement();
       if (valueElement != null) {
         final XmlTag xmlTag = attribute.getParent();
         if (xmlTag != null) {
           final XmlTag referencedTag = JavaFxBuiltInTagDescriptor.getReferencedTag(xmlTag);
           if (referencedTag != null) {
             if (referencedTag.getTextOffset() > xmlTag.getTextOffset()) {
               holder.createErrorAnnotation(
                   valueElement.getValueTextRange(), valueElement.getValue() + " not found");
             } else if (xmlTag.getParentTag() == referencedTag.getParentTag()) {
               final Annotation annotation =
                   holder.createErrorAnnotation(
                       valueElement.getValueTextRange(), "Duplicate child added");
               annotation.registerFix(
                   new JavaFxWrapWithDefineIntention(referencedTag, valueElement.getValue()));
             }
           }
         }
       }
     }
   } else if (element instanceof XmlTag) {
     if (FxmlConstants.FX_SCRIPT.equals(((XmlTag) element).getName())) {
       final XmlTagValue tagValue = ((XmlTag) element).getValue();
       if (!StringUtil.isEmptyOrSpaces(tagValue.getText())) {
         final List<String> langs =
             JavaFxPsiUtil.parseInjectedLanguages((XmlFile) element.getContainingFile());
         if (langs.isEmpty()) {
           final ASTNode openTag = element.getNode().findChildByType(XmlTokenType.XML_NAME);
           final Annotation annotation =
               holder.createErrorAnnotation(
                   openTag != null ? openTag.getPsi() : element, "Page language not specified.");
           annotation.registerFix(new JavaFxInjectPageLanguageIntention());
         }
       }
     }
   }
 }
  private void checkAttribute(XmlAttribute attribute) {
    XmlTag tag = attribute.getParent();

    final String name = attribute.getName();
    PsiElement prevLeaf = PsiTreeUtil.prevLeaf(attribute);

    if (!(prevLeaf instanceof PsiWhiteSpace)) {
      TextRange textRange = attribute.getTextRange();
      addToResults(
          HighlightInfo.createHighlightInfo(
              tag instanceof HtmlTag ? HighlightInfoType.WARNING : HighlightInfoType.ERROR,
              textRange.getStartOffset(),
              textRange.getStartOffset(),
              XmlErrorMessages.message("attribute.should.be.preceded.with.space")));
    }

    if (attribute.isNamespaceDeclaration()) {
      checkReferences(attribute.getValueElement());
      return;
    }
    final String namespace = attribute.getNamespace();

    if (XmlUtil.XML_SCHEMA_INSTANCE_URI.equals(namespace)) {
      checkReferences(attribute.getValueElement());
      return;
    }

    XmlElementDescriptor elementDescriptor = tag.getDescriptor();
    if (elementDescriptor == null
        || elementDescriptor instanceof AnyXmlElementDescriptor
        || ourDoJaxpTesting) {
      return;
    }

    XmlAttributeDescriptor attributeDescriptor =
        elementDescriptor.getAttributeDescriptor(attribute);

    if (attributeDescriptor == null) {
      if (!XmlUtil.attributeFromTemplateFramework(name, tag)) {
        final String localizedMessage =
            XmlErrorMessages.message("attribute.is.not.allowed.here", name);
        final HighlightInfo highlightInfo =
            reportAttributeProblem(tag, name, attribute, localizedMessage);
        if (highlightInfo != null) {
          final XmlFile xmlFile = (XmlFile) tag.getContainingFile();
          if (xmlFile != null) {
            XmlExtension.getExtension(xmlFile).createAddAttributeFix(attribute, highlightInfo);
          }
        }
      }
    } else {
      checkDuplicateAttribute(tag, attribute);

      if (tag instanceof HtmlTag
          && attribute.getValueElement() == null
          && !HtmlUtil.isSingleHtmlAttribute(name)) {
        final String localizedMessage =
            XmlErrorMessages.message("empty.attribute.is.not.allowed", name);
        reportAttributeProblem(tag, name, attribute, localizedMessage);
      }

      // we skip resolve of attribute references since there is separate check when taking attribute
      // descriptors
      PsiReference[] attrRefs = attribute.getReferences();
      doCheckRefs(attribute, attrRefs, attribute.getNamespacePrefix().length() > 0 ? 2 : 1);
    }
  }