default to getting the username from 'email' if present and if not (as the case with okta) use 'preferred_username'
default to getting the username from 'email' if present and if not (as the case with okta) use 'preferred_username'

dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq