title: Setting request headers per request with IHttpClientFactory
body: <p>I'm using typed clients with <code>IHttpClientFactory</code>. Like this:</p>
  
  <pre><code>// Startup.cs
  services.AddHttpClient&lt;MyHttpClient&gt;()
  
  // MyHttpClient.cs
  public class MyHttpClient
  {
      public MyHttpClient(HttpClient client)
      {
          Client = client;
      }
  
      public HttpClient Client { get; }
  }
  
  // MyService.cs
  public class MyService {
      public MyService(MyHttpClient httpClient) {}
  
      public async Task SendRequestAsync(string uri, string accessToken) {
          _httpClient.Client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
          await _httpClient.Client.GetAsync(uri);
      }
  }
  </code></pre>
  
  <p>I'm unsure how this works. Will the request headers be set only for this request, or for every subsequent request that is made using this instance of <code>httpClient</code>. How can I set header on a per request basis?</p>