how to add header in http request in angular 8 code example

Example 1: how to set header in angular 8post

let headers = new HttpHeaders({
    'Content-Type': 'application/json',
    'Authorization': this.basic });
let options = { headers: headers };

Example 2: angular get response headers

this.authenticationService.login(this.f.email.value, this.f.password.value)
  .pipe(first())
  .subscribe(
    (data: HttpResponse<any>) => {
      console.log(data.headers.get('authorization'));
    },
    error => {
      this.loading = false;
    });

At my Service Side.

return this.http.post<any>(Constants.BASE_URL + 'login', {username: username, password: password},
  {observe: 'response' as 'body'})
  .pipe(map(user => {
       return user;
  }));