AuthService - Async HTTP Interceptors with Angular 4

auth.service.ts

import { Injectable } from '@angular/core';
import { UserManager, User } from 'oidc-client';

@Injectable()
export class AuthService {

    private userManager: UserManager;

    constructor () {
        this.userManager = new UserManager({
            // options
        });
    }

    getUser (): Promise<User> {
        return this.userManager.getUser(); // <-- returns a Promise
    }
                                                  
}