@Nullable
  private GenericAttributeValue<PsiClass> findExtensionPointClassAttribute() {
    final DomElement domElement = getExtensionPointClassNameElement();
    if (domElement == null) return null;

    if (domElement instanceof With with) {
      return with.getImplements();
    }
    // only With and GenericAttributeValue<PsiClass> can be returned
    @SuppressWarnings("unchecked")
    GenericAttributeValue<PsiClass> genericAttributeValue = (GenericAttributeValue<PsiClass>)domElement;
    return genericAttributeValue;
  }
@Nullable
  private GenericAttributeValue<PsiClass> findExtensionPointClassAttribute()