🇪🇬Egypt amr_alsayd Cairo
For your case you must enter in
[Advanced -> Others -> Query settings] Row Apath = events
[Fields] JSON_FIELD = event/id
You can debug the all possible values in the render function of this plugin in contribe module 'web/modules/contrib/views_json_source/src/Plugin/views/field/ViewsJsonField.php'
I attached screen shots for debugging to trace the property path