title: URLConnection.getContent with HTML file
body: <p>When I use something like:</p>
  
  <pre><code>URL url = new URL(a_url);
  URLConnection url_conn = url.openConnection();
  Object content = url_conn.getContent();
  </code></pre>
  
  <p>and the MIME type of the file retrieved is HTML or XML I debugged that
  <code>content</code> at run-time will contain an instance of:</p>
  
  <pre><code>sun.net.www.protocol.http.HttpURLConnection$HttpInputStream
  </code></pre>
  
  <p>Now if I want to use <code>instanceof</code> on that instance how can I do?</p>
  
  <pre><code>if (content instanceof PlainTextInputStream)
  {
  ...
  }  
  else if(content instanceof ImageProducer)
  {
  ...
  }
  else if(content instanceof ???) {}
  </code></pre>