public static @Nullable XmlContentDFA createContentDFA(XmlTag parentTag) {
    XmlElementDescriptor descriptor = parentTag.getDescriptor();
    if (descriptor == null) {
      return null;
    }
    XmlElementsGroup topGroup = descriptor.getTopGroup();
    if (topGroup == null) {
      return null;
    }
    return new XmlContentDFAImpl(topGroup);
  }
public static @Nullable XmlContentDFA createContentDFA(XmlTag parentTag)