Remove entries in dav_shares on deletion of a calendar

apps/dav/lib/caldav/caldavbackend.php

@@ -340,6 +340,8 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 
 		$stmt = $this->db->prepare('DELETE FROM `*PREFIX*calendarchanges` WHERE `calendarid` = ?');
 		$stmt->execute([$calendarId]);
+
+		$this->sharingBackend->deleteAllShares($calendarId);
 	}
 
 	/**

apps/dav/lib/carddav/carddavbackend.php

@@ -336,10 +336,7 @@ class CardDavBackend implements BackendInterface, SyncSupport {
 			->setParameter('id', $addressBookId)
 			->execute();
 
-		$query->delete('dav_shares')
-			->where($query->expr()->eq('resourceid', $query->createNamedParameter($addressBookId)))
-			->andWhere($query->expr()->eq('type', $query->createNamedParameter('addressbook')))
-			->execute();
+		$this->sharingBackend->deleteAllShares($addressBookId);
 
 		$query->delete($this->dbCardsPropertiesTable)
 			->where($query->expr()->eq('addressbookid', $query->createNamedParameter($addressBookId)))

apps/dav/lib/dav/sharing/backend.php

@@ -96,6 +96,17 @@ class Backend {
 		$query->execute();
 	}
 
+	/**
+	 * @param $resourceId
+	 */
+	public function deleteAllShares($resourceId) {
+		$query = $this->db->getQueryBuilder();
+		$query->delete('dav_shares')
+			->where($query->expr()->eq('resourceid', $query->createNamedParameter($resourceId)))
+			->andWhere($query->expr()->eq('type', $query->createNamedParameter($this->resourceType)))
+			->execute();
+	}
+
 	/**
 	 * @param IShareable $shareable
 	 * @param string $element