public static @Nullable XmlContentDFA createContentDFA(@NotNull XmlTag parentTag) {
    final PsiFile file = parentTag.getContainingFile().getOriginalFile();
    if (!(file instanceof XmlFile)) return null;
    XSModel xsModel = ReadAction.compute(() -> getXSModel((XmlFile)file));
    if (xsModel == null) {
      return null;
    }

    XSElementDeclaration decl = getElementDeclaration(parentTag, xsModel);
    if (decl == null) {
      return null;
    }
    return new XsContentDFA(decl, parentTag);
  }
public static @Nullable XmlContentDFA createContentDFA(@NotNull XmlTag parentTag)