ontent-Type"</a></code> header of "text/event-stream": This is normal
 operation. <code>onEvent</code> is invoked for each event.  <code>onComplete</code> is invoked when there are no more
 events. <code>onError</code> is invoked only if an unrecoverable error occurs during processing.</li>
 <li>200 - with unsupported or missing <code><a href="../core/HttpHeaders.html#CONTENT_TYPE">"Content-Type"</a></code> header: This is an
 error condition. <code>onError</code> is invoked.</li>
 <li>204 - This indicates 