title: Remove if-modified-since header from okhttp request
body: <p>okhttp sends both <code>if-modified-since</code> date and <code>if-none-match</code> checksum headers in requests. There's usually no need for both and <code>if-none-match</code> is enough to figure out the version the client has. Sending both just confuses some http/1.1 server implementations</p>
  
  <p>I have tried</p>
  
  <pre><code>builder = new Request.Builder().removeHeader("if-modified-since");
  </code></pre>
  
  <p>But that doesn't seem to do it. I assume the header is added later.</p>
  
  <p>Is there a way to tell okhttp not to send <code>if-modified-since</code> ?</p>