Jenkins can execute initialization scripts written in Groovy if they are present during start up. See Groovy Hook Script for details. The hook name for this event is "init".
Those executions happen at the very end of the initialization, and therefore this can be used to pre-configure Jenkins for a particular OEM situation.
While one can always write a plugin to participate in the initialization of Jenkins, this script-based approach can be useful as it doesn't require any compilation and packaging.