The current loging is insufficient level of detial and criticality

upgrade:
Feb 28, 2015 10:49:57 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of GitHub Plugin on behalf of jpyeron
Feb 28, 2015 10:49:57 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading GitHub Plugin
Feb 28, 2015 10:49:58 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Git Client Plugin on behalf of jpyeron
Feb 28, 2015 10:49:59 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Git Client Plugin
Feb 28, 2015 10:50:00 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Git Plugin on behalf of jpyeron
Feb 28, 2015 10:50:00 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Git Plugin
Feb 28, 2015 10:50:01 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Script Security Plugin on behalf of jpyeron
Feb 28, 2015 10:50:02 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Script Security Plugin
Feb 28, 2015 10:50:02 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of JUnit Plugin on behalf of jpyeron
Feb 28, 2015 10:50:02 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading JUnit Plugin
Feb 28, 2015 10:50:02 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Matrix Project Plugin on behalf of jpyeron
Feb 28, 2015 10:50:03 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Matrix Project Plugin
Feb 28, 2015 10:50:03 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Mailer on behalf of jpyeron
Feb 28, 2015 10:50:03 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Mailer
Feb 28, 2015 10:50:03 AM hudson.model.UpdateCenter$DownloadJob run
INFO: Starting the installation of Git Client Plugin on behalf of jpyeron
Feb 28, 2015 10:50:04 AM hudson.model.UpdateCenter$UpdateCenterConfiguration download
INFO: Downloading Git Client Plugin
Feb 28, 2015 11:20:02 AM hudson.model.UpdateCenter doSafeRestart
INFO: Scheduling Jenkins reboot

downgrade:
Feb 28, 2015 12:28:10 PM hudson.model.UpdateCenter$PluginDowngradeJob run
INFO: Starting the downgrade of Matrix Project Plugin on behalf of anonymous
Feb 28, 2015 12:28:10 PM hudson.model.UpdateCenter$PluginDowngradeJob run
INFO: Downgrade successful: Matrix Project Plugin

The upgrade and downgrade actions need to log the old and new version numbers for each plugin change at the warning level, to ensure it being recorded to the log.

See thread https://groups.google.com/d/msgid/jenkinsci-users/CAO49JtFuG9t_F4zL%3D7ncg53XdZG9dZD-GdWQ1dtTN53DrKjm8g%40mail.gmail.com