Override Src Core classes v8

Developing with Concrete
1

I would like to override concrete/src/Calendar/Event/Formatter/DateFormatter.php
What’s the proper way to do this?

Because with Override (almost) any core file in Concrete CMS I can’t figure out how.

Tried several things found in docs (see below) but sometimes it’s not clear if more core files need to be overridden before another override will work.

2

What did you try and didn’t work?

3

I tried the legacy methods mentioned here:

and here:
https://documentation.concretecms.org/developers/framework/extending-concrete5-with-custom-code/creating-custom-code-in-the-application-directory

And this one:
hxxps://documentation.concretecms.org/developers/framework/extending-concrete5-with-custom-code/extending-core-classes-in-the-application-directory

But no result. Sometimes it’s not clear for which cms version the code is applicable to.

But from past experiences I know it sometimes takes more than just changing/overriding 1 file.

I’m using version 8.5.7