Hi @Grzesiek2010: thanks for your quick response.
I am working with my own fork, and intend to add the Install ID to the querystring in the form list request. My fork works with my own custom server, and has historically used the DeviceID/IMEI (or wifi MAC address for non-IMEI devices) to identify the user in the querystring, so as to offer a form list customised for each user: see this post in the thread you mentioned. In the current version of my app (forked from Collect 1.8 - I don't update it very often!) the IMEI is already inaccessible when running on Android10 devices.
I did find the SharedPreferencesInstallIDProvider, and after some hacking about managed to obtain the stored InstallID using this code:
SharedPreferences prefs = new MetaSharedPreferencesProvider(this).getMetaSharedPreferences();
SharedPreferencesInstallIDProvider myprefs = new SharedPreferencesInstallIDProvider(prefs,KEY_INSTALL_ID);
String InstallID = myprefs.getInstallID();
But just because it works doesn't mean it's the right way to go about it! I'm very unfamiliar with the complexities of Android, and concerned that a bad implementation by me might break in a later version of Collect - so does this look like a sensible solution?
Grateful for any advice!
Nik