@Override
  public void addListField(String fieldName, PdxListHelper list) {
    if (logger.isTraceEnabled()) {
      logger.trace("addListField fieldName: {}", fieldName);
    }
    m_pdxInstanceFactory.writeObject(fieldName, list.getList());
    addIdentityField(fieldName);
  }
This class is intermediate class to create PdxInstance.
geode-core/src/main/java/org/apache/geode/pdx/internal/json/PdxInstanceHelper.java