code: void writeEntryCategory(Object entity) throws XMLStreamException {
  
          Type entityType = entityDataModel.getType(entity.getClass());
          xmlWriter.writeStartElement(ATOM_CATEGORY);
          xmlWriter.writeAttribute(SCHEME, ODATA_SCHEME_NS);
          xmlWriter.writeAttribute(TERM, String.format("%s%s.%s", HASH, entityType.getNamespace(), entityType.getName()));
          xmlWriter.writeEndElement();
      }
docs: Write a {@code <category>} element for a given entity.
  
  @param entity The given entity.
  @throws XMLStreamException If unable to write to stream