Describe the bug
Best solution consumer of solver manager is fired before deep clone of the planning solution has been completed. This lead to problems if you need to post-process the data returned from timefold solver. I recognized it because timefold throws in some cases IllegalStateExecption with "Verify the consistency of your input problem for that bi-directional relationship." message if I manually change content of bi-directional data.

Expected behavior

1. Planning Solution gets first deep cloned
2. Best Solution consumer is triggered after deep clone is completed. So it is safe to manipulate the Solution passed to best solution consumer.

Actual behavior
Planning Solution consumer and deeclone running in different thread and are not synchronized. If you edit a planning solution in the solution consumer it can influence the running planning if the edit took place before deepclone happend.

To Reproduce

1. Create a Planning with a PlanningEntity having a bi-directional relationship(invers Shadow Variable)
2. Start solving with solver manger and add a best solution consumer
3. In best solution consumer change one side of the bi directional relation ship
4. Wait for the IllegalStateException. It happens only if bestSolutionConsumer thread is faster than the thread executing the planning

Environment

Timefold Solver Version or Git ref: 1.21.0

Output of java -version: Eclipse Temurin JDK 21.0.6+7-LTS

Output of uname -a or ver: 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan 2 20:24:23 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6020 arm64

Additional information

Provide any and all other information which might be relevant to the issue.