Remove custom optional serializer

[lagom]

Remove custom optional serializer

[lakhina]

@ignasi35 Not sure if you are pointing toward these https://github.com/lagom/online-auction-java/blob/master/user-api/src/main/java/com/example/auction/user/api/User.java#L17

[ignasi35]

Hi @lakhina. This issue refers to the serialization engine behind the persistence layer.

Lagom uses two different serialization solutions: one for the service layer (API) and another one to exchange information between the nodes of the akka cluster (pubsub, akka-persistence, etc...).

This issue refers to the later.

Some back-story:

• Akka provided serializers for several well-known types in both scala and java. Unfortunately, java.util.Optional was not on that list originally. In order to implement a Lagom persistent entity where a State could be Optional<MyBasketOrder> (or Optional<PItem>) a serializer for java's Optional was required. While it was not provided in Akka itself we developed our own for the online-auction app. Currently akka provides one so we should remove our custom serializer and let akka's pick up.

[lakhina]

@ignasi35 From my understanding at this point we have to replace usage of com.lightbend.lagom.serialization with usage of serialization from akka.
Am I going wrong?

[ignasi35]

@lakhina we have to make sure [JOptionalSerializer](https://github.com/lagom/online-auction-java/blob/b6bea26afad45461a43c437dfd8ea70e52d783a4/item-impl/src/main/java/com/example/serializer/JOptionalSerializer.java) (and related code) is removed but the application still works. ;-)