com.liferay.portal.kernel.upgrade
Interfaces 
UpgradeStep
Classes 
BaseUpgradeAdminPortlets
BaseUpgradeLastPublishDate
BaseUpgradePortletPreferences
CamelCaseUpgradePortletPreferences
DummyUpgradeStep
MockPortletPreferences
RenameUpgradePortalPreferences
RenameUpgradePortletPreferences
UpgradeProcess
Exceptions 
OlderVersionException
StagnantRowException
UpgradeException