@Override
  public DomExtension setDeclaringElement(@NotNull PsiElement declaringElement) {
    putUserData(DECLARING_ELEMENT_KEY, SmartPointerManager.getInstance(declaringElement.getProject()).createSmartPsiElementPointer(declaringElement));
    return this;
  }
@Override
  public DomExtension setDeclaringElement(@NotNull PsiElement declaringElement)