"force online index build to backoff and retry DML lock upgrade"
*Action: set this event only under the supervision of Oracle development
*Comment: Change the behaviour of an online index rebuild such that it
will backoff and retry a failed DML lock upgrade.
The event level is the number of retries the online index rebuild
should wait. Level 1 means backoff and retry indefinitely. Any
other value less than 32 will be adjusted automatically to be 32.