The successors of AbstractKeyValueObjectDataHandler are the default handler for reading and writing key value data (e.g. JSON).
The KeyValueDataHandler stores the key value pairs with a flat structure in one map in a KeyValueObject, in contrast to the NestedKeyValueObjectDataHandler, which stores the key value pairs in nested maps in a NestedKeyValueObject.
Functionality of this two slightly different handlers should be the same, but may differ in performance depending on use case.