Review WhatsApp Message compareTo() to avoid "Comparison method violates its general contract" exceptions.

[wladimirleite]

Fix #2337.

[wladimirleite]

I just noticed that there is a test case failing after this fix.
For now, I converted it to draft and will push a fix shortly.

[wladimirleite]

Unit tests are working again.
I tested with 4 database samples (Android old, new, iOS and an Android that I have the device here), and the result seems fine.

[lfcnassif]

Thank you @wladimirleite! Just to confirm commit 39c1a37 is good, right?

[wladimirleite]

Thank you @wladimirleite! Just to confirm commit 39c1a37 is good, right?

No! Sorry, I will fix it.

[wladimirleite]

Thank you @wladimirleite! Just to confirm commit 39c1a37 is good, right?

No! Sorry, I will fix it.

I believe it is correct (and a bit clearer) now.
I am sorry for the last wrong commits, @lfcnassif...
I was doing other things in parallel and messed up.

Priority order should be: sortId -> timeStamp -> id.
For new databases, sortId is usually present in all records. For older ones, no sortId, but timeStamp is always present.
In practice, the fallback is only used in very specific cases, only between sortId and timeStamp.

[lfcnassif]

Thanks @wladimirleite!