private PdxInstance createPdxInstance() {
    Collections.sort(fieldList);
    PdxInstanceFactory factory = createPdxInstanceFactory();
    for (JSONFieldHolder<?> f : fieldList) {
      filldata(factory, f);
      addIdentityField(factory, f.fieldName);
    }
    return factory.create();
  }
This class is intermediate class to create PdxInstance.
geode-core/src/main/java/org/apache/geode/pdx/internal/json/PdxInstanceSortedHelper.java