@Override
    public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
      Extension fixExtension = DomUtil.findDomElement(descriptor.getPsiElement(), Extension.class, false);
      if (fixExtension == null) return;

      XmlTag xmlTag = fixExtension.getXmlTag();
      XmlTag languageTag = xmlTag.createChildTag("language", null, myAnyLanguageID, false);
      XmlTag addedLanguageTag = xmlTag.addSubTag(languageTag, true);
      if (!IntentionPreviewUtils.isPreviewElement(addedLanguageTag)) {
        PsiNavigationSupport.getInstance()
          .createNavigatable(project, addedLanguageTag.getContainingFile().getVirtualFile(),
                             addedLanguageTag.getValue().getTextRange().getEndOffset()).navigate(true);
      }
    }
@Override
    public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor)