How to convert a MySQL 5.7 JSON NULL to native MySQL NULL?

Unfortunately CAST('{}' AS JSON) will not work is this case, but NULLIF works:

1. Full methods:

   SELECT NULLIF(JSON_UNQUOTE(JSON_EXTRACT('{"hello": null}', '$.hello')), 'null') IS NULL;

2. Shorted:

   SELECT NULLIF(helloColumn ->> '$.hello', 'null') IS NULL IS NULL;