Add a doc why this should not be removed

Signed-off-by: Joas Schilling <coding@schilljs.com>

3 files changed, 15 insertions, 3 deletions

diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php b/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php
index 1efdbb13b8c..fb4a0ff45a8 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Calendar.php
@@ -201,7 +201,11 @@ class Calendar extends Base {
 			}
 		}
 
-		// Legacy
+		// Legacy - Do NOT Remove unless necessary
+		// Removing this will break parsing of activities that were created on
+		// Nextcloud 12, so we should keep this as long as it's acceptable.
+		// Otherwise if people upgrade over multiple releases in a short period,
+		// they will get the dead entries in their stream.
 		switch ($subject) {
 			case self::SUBJECT_ADD:
 			case self::SUBJECT_ADD . '_self':
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Event.php b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
index dafd2404d2f..7b515d78b14 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Event.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
@@ -139,7 +139,11 @@ class Event extends Base {
 			}
 		}
 
-		// Legacy
+		// Legacy - Do NOT Remove unless necessary
+		// Removing this will break parsing of activities that were created on
+		// Nextcloud 12, so we should keep this as long as it's acceptable.
+		// Otherwise if people upgrade over multiple releases in a short period,
+		// they will get the dead entries in their stream.
 		switch ($subject) {
 			case self::SUBJECT_OBJECT_ADD . '_event':
 			case self::SUBJECT_OBJECT_DELETE . '_event':
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Todo.php b/apps/dav/lib/CalDAV/Activity/Provider/Todo.php
index 0f9cd640537..20d7afef028 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Todo.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Todo.php
@@ -112,7 +112,11 @@ class Todo extends Event {
 			}
 		}
 
-		// Legacy
+		// Legacy - Do NOT Remove unless necessary
+		// Removing this will break parsing of activities that were created on
+		// Nextcloud 12, so we should keep this as long as it's acceptable.
+		// Otherwise if people upgrade over multiple releases in a short period,
+		// they will get the dead entries in their stream.
 		switch ($subject) {
 			case self::SUBJECT_OBJECT_ADD . '_todo':
 			case self::SUBJECT_OBJECT_DELETE . '_todo':