query: 2.0.0 - (GREEN) Values are serialized as JSON

--
works __only__, if a default-type is defined

* The default-type is needed, to deserialized values that are read from the
  state-store.
* Without it, the deserialization fails, because not type-information is
  available.
* The type-information gets lost, when the values are stored in the state-
  store, because the message-headers are _not_ stored along with the value!