If the proxy server does not require authentication, user can go to Web Administration security page and configure the following settings .

If the proxy server requires authentication , User will need to add clientToken="true" in the apps tag as listed below in the mapConfig.xml file located under plugins\ConnectorForESRIMap\WEB-INF\xml\config (see sample below).
Note: Restart the web server after this change .
<ec> <apps clientToken="true"> <key><![CDATA[------]]></key> </apps> </ec>
