Apart from that, if a mozillian user has selected in his Mozillian profile not to share his data with other Mozilla apps, the username field is not included in the data with receive. The only data that we get from the API is his vouched status. The only alternative would be to populate the `mozillian_username` field with a default string. The reason that I chose to have as a default value the one of an empty string is to be able to evaluate this in jinja templates to `False` and in code in general.