@Override
  protected String rewriteQueryStringFromRequest(HttpServletRequest servletRequest, String queryString) {
    return (String) servletRequest.getAttribute(ATTR_QUERY_STRING);
  }
A proxy servlet in which the target URI is templated from incoming request parameters. The
format adheres to the <a href="http://tools.ietf.org/html/rfc6570">URI Template RFC</a>, "Level
1". Example:
<pre>
  targetUri = http://{host}:{port}/{path}
</pre>
--which has the template variables.  The incoming request must contain query args of these
names.  They are removed when the request is sent to the target.
src/main/java/org/mitre/dsmiley/httpproxy/URITemplateProxyServlet.java