Why is it implemented in this file instead of be part of core?
To remember, this file should contain exclusively what it mandatory to run Ng generation and the add of Otter core.
If it is not the case of these file updates you may need to move them in core.

I also think that in any case, as the generators require to be have the lf constrain, the core schematics should do this update (as well if it is mandatory here).

For me, this file it's part of the monorepo configuration, I would expect to have it defined directly when I create the monorepo.
I don't expect it to change when someone run ng add @o3r/core on an exisiting monorepo.

What do you think about that @AmadeusITGroup/otter_admins ?

I also think this should only be generated at create time, not on ng add

Same as Florian and Matthieu. I would not mess with an existing project.
It makes sense to change it when the editorconfig file is created, and in this case the file is created during the angular create script.

But this is not at all the purpose of the create script.
If it is a mandatory for our generators then as soon as we add Otter to a project we may need this change.
If it is not, but part of the Otter guidelines, then it should be bring by a ng add (even if it is done only once).

Please remember that the create script is only to initialize a ng repo and start an Otter setup, it should remain as simple as possible and it should not be the one applying guidelines (or setup default value) that would not be available to people who are not generating the repository from scratch with the create.

For me the correct behavior is the following one:
On Otter setup, if the .editorconfig file is present, we default the value of [*].end_of_line to lf (if no value already set). If the file does not exist, we create if root: true and [*].end_of_line: true.
(same logic for .gitattributes file).

Not sure to understand this option.
If it is needed, you should also provide documentation regarding it in readme.
(and potentially tests :D)

It is already documented here, you can go on this link https://v17.angular.io/cli/new#options

In their case they are not generating the .editorconfig if they have the option minimal set to true

It is already documented here, you can go on this link v17.angular.io/cli/new#options

This is not really a fare answer :D.
The option itself is not documented but, as part of Angular option, is supported.
I think you can add a comment (with a link potentially) in the code regarding it.

In their case they are not generating the .editorconfig if they have the option minimal set to true

Would be worse to add it as comment as well in the code