I have an ongoing migrate_d2d migration where I will need to be able to detect changes on a node by node basis, and I would really like to be able to use the functionality in the Hash source rows to detect changes feature to do that. However, I can't find where to add that option so that the hashes are generated. I've tried this is my class (that overrides DrupalNode6Migration):
$this->sourceOptions['track_changes'] = TRUE;
but the option isn't added and used. According to this referenced post on this feature, I should add it in my source constructor, but that part is handled by migrate_d2d in the abstract DrupalMigration class. Do I need to go down to that level to create my class just to access this property, or is there a way I can add it from my class that overrides Drupal6NodeMigration?