title: Resharper: Possible null assignment to entity marked with notnull attribute
body: <p>I get this warning on <code>response.GetResponseStream()</code>
  How should I handle this?</p>
  
  <pre><code>// Get response  
  using (var response = request.GetResponse() as HttpWebResponse)
  {
      // Get the response stream  
      if (response != null)
      {
          var reader = new StreamReader(response.GetResponseStream());
          var responseString = reader.ReadToEnd();
          return responseString;
      }
  }
  </code></pre>
  
  <p><strong>For clarity based on some answers misinterpreting</strong>:</p>
  
  <p>This line is <strong>not</strong> where the warning is occurring:  </p>
  
  <pre><code>using (var response = request.GetResponse() as HttpWebResponse)
  </code></pre>
  
  <p>This line <strong>is</strong> where the warning is occurring:</p>
  
  <pre><code>var reader = new StreamReader(response.GetResponseStream());
  </code></pre>