How could I get the email attribute from the Group Members API?

Dear Sir

I want to use the Gitlab API to get the email attribute of a user(group members).

I got member information from groups following this API.

/groups/:id/members

But I cannot get only the email attribute.

As stated in the API reference, the email is set to public in the user settings.

I have made the emails of members of my group public.

However, still I cannot get menbers email attribute.

There is no further information in the references and it does not change what should be done.

Do I need to set my account to premium or something?

Please I would like to get some advice.

Kind regards

Masa