I implemented the new Privacy API functions (https://docs.moodle.org/dev/Moodle_3.6_release_notes#Privacy_API_update) in my plugin, and backported it so that it would run on Moodle 3.5, 3.4 and 3.3. While it seems to run fine, apparently it kills the Plugin privacy registry page with the error:
Fatal error: Interface 'core_privacy\local\request\core_userlist_provider' not found in /ocfs2/www/owko/mod/questionnaire/classes/privacy/provider.php on line 30
It looks like this is because the core_userlist_provider is not in the previous releases of Moodle (pre 3.5.3, pre 3.4.6 and 3.3.*). This becomes a problem is someone upgrades the plugin prior to upgrading Moodle. And, this will fail on 3.3 completely.
Is there a way to keep my plugin backward compatible to prior releases and not cause this error?