Where to find API files of OCS or API documentation?

Hey guys,
so I wanted to contribute to Nextcloud but don’t have much experience with Vue and none with PHP.
I want to implement the missing feature of renaming groups (see Issue). I think I have got the Vue part working but now need to make the call to the backend. As fas I can see the actual backend functionality is already present. But what I can not find is the API endpoint to make the call to.

Is there any documentation for that or could somebody point me to the right files in the code to look at?
I found this but am not sure what the API path to that would be.

Thanks for the help!

Anyone got any suggestions?

I don’t know if this helps, but:

OCP is translated to OwnCloudPublic, those files lie in server directory lib/public
OC is translated to OwnCloudPrivate, those files lie in server directory lib/private
OCA is translated to OwnCloudApps, those files lie in server directory apps

These translations are not defined anywhere, I just assumed they work like this based on searching the source files.

So your file ISetDisplayNameBackend would be located in /lib/public/Group/Backend/ ISetDisplayNameBackend.php

If you put this in your constructor and it gets initialised, it will probably be a private class SetDisplayNameBacked (without the “I” at the beginning), which might actually store the source code of what it is supposed to do:
/lib/private/Group/Backend/ SetDisplayNameBackend.php

Thank you very much!
Because I didn’t get an answer here, I asked again in the issue a couple days ago and got an answer.

I never thought of looking into the provisioning api app. Because I found the backend code, like you described, in the core.