https://github.com/aipocom/aipo/blob/2546138b64339cd2ad677d55cc0f6a9ea621aae0/jetspeed/src/main/java/org/apache/jetspeed/portal/portlets/ServletProxyPortlet.java#L127-L131
以下のへんに記述があります。
String token = getPortletConfig().getInitParameter(SESSION_TOKEN_PARAMETER_NAME); if(token == null) { token = DEFAULT_SESSION_TOKEN; } servletURL = protocol + "://" + rundata.getServerName() + ":" + rundata.getServerPort() + rundata.getContextPath() + servletURL + ";" + token + "=" + rundata.getSession().getId() + queryString;