Nested include test coverage is inadequate wrt "include permissions"

Another reason you can plainly see this is wrong:

  protected static function getIncludePermissions() {
    return [
      'uid.node_type' => ['administer users'],
      'uid.roles' => ['administer permissions'],
    ];
  }

uid.node_type does not exist, and to access the roles field of User entity type, one needs the administer users permission, not the administer permissions.

#2953321: Comprehensive JSON API integration test coverage phase 5: nested includes and sparse field sets introduced this, not sure what went wrong there. But that was a very big issue, perhaps it was simply overlooked there.