public @Nullable XmlElementDescriptor getDescriptorByType(String qName, XmlTag instanceTag){
    if(myTag == null) return null;
    final TypeDescriptor typeDescriptor = findTypeDescriptor(qName, instanceTag);
    if(!(typeDescriptor instanceof ComplexTypeDescriptor)) return null;
    return new XmlElementDescriptorByType(instanceTag, (ComplexTypeDescriptor)typeDescriptor);
  }
public @Nullable XmlElementDescriptor getDescriptorByType(String qName, XmlTag instanceTag)