There are problem to fetch CPA?

Hi. I tried to build my own plugin and found that CPA (custom profile attributes) not shared with p.API.GetUser() feature.. So, can u tell me how I should fetch CustomProfileAttributes on the server back end correctly?
And I read mattermost/server/public/model/custom_profile_attributes.go at server/public/v0.1.21 · mattermost/mattermost · GitHub but nothing to understand with it and how it should be working:\