/// <summary>
 /// Adds headers to the built HTTP request message.
 /// </summary>
 /// <param name="headers">Headers represented by HttpRequestHeaders type.</param>
 /// <returns>The same HTTP request message builder.</returns>
 public IAndHttpRequestMessageBuilder WithHeaders(HttpRequestHeaders headers)
 {
     headers.ForEach(h => this.requestMessage.Headers.Add(h.Key, h.Value));
     return this;
 }