Updates the webapp descriptor by injecting portlet wrapper servlet
definitions and mappings.
Parameters: webXmlIn - input stream to the webapp descriptor, it will be closed before the web xml is written out. Parameters: portletXmlIn - input stream to the portlet app descriptor, it will be closed before the web xml is written out. Parameters: webXmlOut - output stream to the webapp descriptor, it will be flushed and closed. Parameters: dispatchServletClass - The name of the servlet class to use forhandling portlet requests throws: IOException -