angular 8 Http POST with content type application/x-www-form-urlencoded

import { HttpClient, HttpHeaders } from '@angular/common/http';

postData(url: string, data: any) {
  const headers = new HttpHeaders().set('Content-Type', 'application/x-www-form-urlencoded');
  return this.http.post(url, this.transformRequest(data), { headers });
}

transformRequest(obj: any) {
  const formData = new FormData();
  for (const key in obj) {
    if (obj.hasOwnProperty(key)) {
      formData.append(key, obj[key]);
    }
  }
  return formData;
}

const url = 'https://example.com/api';
const data = {
  username: 'john',
  password: 'secret'
};

this.postData(url, data).subscribe(response => {
  console.log(response);
}, error => {
  console.error(error);
});