I don’t think this is a good idea, especially because it breaks the whole sync logic and is a dirty hack and creates behavior which can’t be understood by users.
no problem - our users (corporate users connecting to openCRX) are actually more disturbed by the fact that the sync process breaks because of the various 403-Forbidden messages - as long as an address book (or it’s contacts, respectively) cannot be locked down properly if a collection is marked as read-only, it’s just a matter of time until the client doesn’t sync anymore because the user (or some other app running on the device) has made changes to a contact…
anyway, we have adapted the behavior on the server-side such that DAVdroid does not receive 403-Forbidden anymore - the server claims to accept the create- or update-request but actually ignores it and ensures that any (forbidden) changes on the Android devices are simply undone with the next sync (from the admin’s perspective it’s much better to annoy/educate the user than to break the sync account)
and ideally Android gets it’s act together and supports read-only contacts and/or address books
Thanks for the hint, I’ve added it to the roadmap for DAVx⁵:
As you can see, there are a lot of possible enhancements, so maybe this will take while…