Describe the bug
Example:
Project has Collection of Radio

We load a radio (call it radio1) from the database with together with a project (call it project1). Then we create a new project or do something else and we persistAndFlush it. Then it also finds a diff on radio1 that the project_id has changed to project1.id. This is weird, since it has not changed.

This triggers an additional and unnecessary query to update radio1.

To Reproduce
Steps to reproduce the behavior:

1. Checkout PR 1333
2. yarn test GH1334
3. ...

Expected behavior
Should not trigger an update query on radio1

Additional context
When setting the LoadStrategy to SELECT_IN it does not trigger the additional update query