title: Refit and authorization header
body: <p>Currently, I am adding an authorization header to my request like this:</p>
  
  <p>File: SomeFile.cs</p>
  
  <pre><code>public interface ITestApi
  {
      [Get("/api/test/{id}")]
      Task&lt;string&gt; GetTest([Header("Authorization")] string authorization, int id);
  
      [Get("/api/tests/")]
      Task&lt;string&gt; GetTests([Header("Authorization")] string authorization);
  }
  </code></pre>
  
  <p>File: SomeOtherFile.cs</p>
  
  <pre><code>var username = "xxx";
  var password = "yyy";
  var authHeader = "Basic " + Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes(username + ":" + password));
  var baseAddress = "https://my.test.net";
  ITestApi myApi = RestService.For&lt;ITestApi&gt;(baseAddress);
  
  int id = 123;
  var test= myApi.GetTest(authHeader, id);
  
  var tests = myApi.GetTests(authHeader);
  </code></pre>
  
  <p>Is there a way to set the authHeader globally so that I don't have to pass it as a parameter to every call? (I am using Refit version 4.6.48). In other words, I'd like to be able to do the calls like this:</p>
  
  <pre><code>var test= myApi.GetTest(id);
  
  var tests = myApi.GetTests();
  </code></pre>