@Override
  public void invoke(@NotNull Project project, Editor editor, @NotNull PsiElement element) throws IncorrectOperationException {
    final XmlTag tag = (XmlTag)element.getParent();
    final String value;
    if (tag.getSubTags().length == 0) {
      value = tag.getValue().getText().trim();
    }
    else {
      value = StringUtil.join(tag.getSubTags(), childTag -> {
        final XmlAttribute valueAttr = childTag.getAttribute(FxmlConstants.FX_VALUE);
        if (valueAttr != null) {
          return valueAttr.getValue();
        }
        return "";
      }, ", ");
    }
    final XmlAttribute attribute = XmlElementFactory.getInstance(project).createXmlAttribute(tag.getName(), value);
    final XmlTag parentTag = tag.getParentTag();
    if (parentTag != null) {
      parentTag.add(attribute);
      tag.delete();
    }
  }
@Override
  public void invoke(@NotNull Project project, Editor editor, @NotNull PsiElement element)