Issue #3074047 by Neslee Canil Pinto, mikelutz, quietone: Update...

Issue #3074047 by Neslee Canil Pinto, mikelutz, quietone: Update MigrateDestinationInterface::import return type documentation

(cherry picked from commit bbbed21e)

core/modules/migrate/src/Plugin/MigrateDestinationInterface.php

@@ -103,8 +103,11 @@ public function fields(MigrationInterface $migration = NULL);
    * @param array $old_destination_id_values
    *   (optional) The old destination IDs. Defaults to an empty array.
    *
-   * @return mixed
-   *   The entity ID or an indication of success.
+   * @return array|bool
+   *   An indexed array of destination IDs in the same order as defined in the
+   *   plugin's getIds() method if the plugin wants to save the IDs to the ID
+   *   map, TRUE to indicate success without saving IDs to the ID map, or
+   *   FALSE to indicate a failure.
    */
   public function import(Row $row, array $old_destination_id_values = []);