Register Setting validation not working.

[devanddhiraj]

register_setting validation not working (validation function does not called)
register_setting( $this->parent->_token . '_settings', $option_name, $validation);

[rafasashi]

Good point!

There is no such thing as $validation parameter in the first place.

According to the doc it should be passed into $args['sanitize_callback']:

https://developer.wordpress.org/reference/functions/register_setting/