let someInfo: SomeInfo = new SomeInfo("abc", "xyz");

this.httpclient.post<MwUser>(apiUrl, someInfo).subscribe(
  res => {
    console.log(res);
  },
  error => {
    console.log(error);
  }
);

const paramToPass: any = new HttpParams().set('groupType', 'xyz');
this.httpclient.post<MwUser>(apiUrl, someInfo, paramToPass).subscribe(
  res => {
    user = res;
    console.log(res);
  },
  error => {
    console.log(error);
  }
);