[java] Add tips and tricks section

[vmikhailenko]

Opens a FAQ section with one nasty corner-case that we discovered internally. Just so we can later reference to it.

[BraunMatthias]

should this section rather focus on avoid expensive joins by providing the foreign key to associated entities instead of associated entity values (example with user name)? The name can be resolved when reading the logs on basis of the id.

[vmikhailenko]

We never documented the runtime manipulation of changelog.

I could add a little explainer. Something like: if you need custom identifier, write an handler...

[BraunMatthias]

I think the remote scenario is not valid - it's rather about how to deal with associated entities with best possible performance. User (as Remote) would be a nice example: the user.id FK can be resolved at READ time of the ChangeLog, but creation of logs would be much cheaper if no join is required to Users.

[BraunMatthias]

Optimize Changelogs for Associated Entities