Persistence with Jackson trying to cast all Map keys to String

Description

akka {
  actor {
    serializers {
      jackson-json = "akka.serialization.jackson.JacksonJsonSerializer"
      jackson-cbor = "akka.serialization.jackson.JacksonCborSerializer"
    }
    serialization-bindings {
      "xxx.CborSerializable" = jackson-cbor
    }
  }
}

trait CborSerializable

final case class State(data:Map[Long,List[String]]) extends CborSerializable

// persist something with typed persistent actor.  eg. 42 -> List() 
// after snapshot recovery 

state.data.get(42) // should be Some, but it is None

state.data.find(_._1 == 42) // throws ex

Contributor guide

Tech stack

java

Domain

backend

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

half day

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

ScalaAkka serialization

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

40

Research direction

Investigate the Jackson configuration in Akka's serialization module, specifically how ObjectMapper is configured for key serialization. Check the JacksonJsonSerializer and JacksonCborSerializer source code for any custom type resolvers or key serializers. The bug occurs because Jackson by default serializes map keys as strings, causing a ClassCastException when the key type is Long. Consider providing a custom key serializer or enabling Jackson's default typing for map keys. The fix likely involves modifying the ObjectMapper setup in Akka to handle non String map keys correctly.