Current Documentation of changing the session expiry is incorrect. The current documentation involves changing the value of servlet named 'clean_expired_sessions' present in the web.xml file located at <Mingle_installation_directory>/config. The correct steps to change the session expiry are as below:
1. Stop the MingleServer.
2. Edit the file session.rb file located at <Mingle_Installation_Directory>/config/initializers
"Session.expires = 4.hours" ( replace 4 with the number of your preference)
3. Save the file and restart Mingle Server.
NOTE: The documentation will be changed to reflect the correct steps in Mingle 3.3.