OpenID provider does not provide nickname and email
Adding openid.sreg.optional=nickname%2Cemail to the redirect URL does not result in getting back those information from GNUSocial, and verification also still pass if openid.sreg.required is passed, which should instead fail if the identity owner does not want to grant access to those info.
See https://github.com/yohcop/openid-go/issues/44#issuecomment-275852619 for more info (SimpleID works fine)