This is the final step in deprecating the subplugins 'ltisource' and 'ltiservice'.

For this to be possible, we need:

1. A formal plugintype deprecation strategy (MDL-79843 deals with adding this)
2. To have migrated the backup and restore code from mod_lti to core_ltix. This point is only necessary to prevent unit test failures due to the use of add_subplugin_structure('ltiservice') or add_subplugin_structure('ltisource') within existing mod/lti backup code.

Once the above is done, this should be as simple as adding the following to mod/lti/db/subplugins.json (and removing 'plugintypes' entirely):

...

"deprecatedplugintypes": {

    "ltiservice": "mod\/lti\/service",

    "ltisource": "mod\/lti\/source",

}

Historical

Some info originally on this issue's description (no longer relevant but updated to say why):

Backup locations that need to be considered:

• mod/lti/backup
• mod/lti/service/gradebookservices/backup
  • All backup and restore considerations will be addressed in the issues dealing specifically with backup and restore.

Other things to take into account:

• if we end up removing subplugin support without deprecation, remove any relevant code in mod/lti/ (callbacks, settings, backup, etc.)
  • Removing the uses of subplugins isn't in the scope of this issue and will have been handled in other issues (like the migration + cleanup of ltiservice and ltisource)
• if we end up deprecating subplugins + subplugin type (preferred approach), make sure we update core_ltix code that's calling the 'ltixservice' callbacks. We'll want to do this, and then fall back to the deprecated 'ltisource' plugins within mod/lti in cases where the ltix method isn't found. This is basically "prefer ltixsource, support ltisource".
  • All subplugins are deemed end of life and must be migrated to ltixservice and ltixsource. This will be documented as part of the release.

For ltiservice subplugins:

MDL-80231 dealt with the final clean up of ltiservice code from mod/lti, but left the following stuff as TODOs for this issue:

1. mod/lti/db/subplugins.json - there's still an ltiservice entry in here, likely because we'll use it here to mark the subplugin type as deprecated.
2. mod/lti/lang/en/lti.php: where the strings 'subplugintype_ltiservice' and 'subplugintype_ltiservice_plural' still exist to describe the subplugins (which we may still need if we're showing them in the UI, tbc)
3. mod/lti/classes/plugininfo/ltiservice.php: plugininfo for the subplugin - likely still needed, but may be able to delete, tbc
4. mod/lti/upgrade.txt - need to add an upgrade note when we've finally deprecated the subplugin types

For ltisource subplugins:

The remaining mod/lti files need to be addressed (these have references to ltisource and have not been addressed in MDL-79115):

1. mod/lti/backup/moodle2/backup_lti_stepslib.php (backup/restore handled elsewhere)
2. mod/lti/backup/moodle2/restore_lti_stepslib.php{} (backup/restore handled elsewhere){}
3. mod/lti/classes/plugininfo/ltisource.php
4. mod/lti/db/subplugins.json
5. mod/lti/lang/en/lti.php
6. mod/lti/mod_form.php (updating callbacks to use ltix will have been done elsewhere)
7. mod/lti/settings.php (not part of this issue's scope. any callbacks in settings will have been handled elsewhere as part of moving the settings to core)