*
* @var int[]
*/
- public $core = [];
+ public $core;
+
+ /**
+ * Identifies the system providing the data the field plugin will read.
+ *
+ * The source_module is expected to be the name of a Drupal module that must
+ * must be installed in the source database.
+ *
+ * @var string
+ */
+ public $source_module;
+
+ /**
+ * Identifies the system handling the data the destination plugin will write.
+ *
+ * The destination_module is expected to be the name of a Drupal module on the
+ * destination site that must be installed.
+ *
+ * @var string
+ */
+ public $destination_module;
}