Is your feature request related to a problem? Please describe.
It is currently not possible to make OpenTripPlanner return a delay for an ADDED or REPLACEMENT trip in GTFS-RT. If both a time and a delay is specified in the StopTimeEvent in GTFS-RT, the latter is ignored as per GTFS-RT spec, in line with SCHEDULED trips.

Goal / high level use-case
A transport provider wants to add last-minute event special which does not exist in the GTFS static timetable, and the bus may be delayed.

Describe the solution you'd like
OpenTripPlanner should handle both time and delay in an StopTimeEvent for added or replacement trips (where the behaviour is not specified in the official GTFS-RT specification).

Describe alternatives you've considered
Implement the GTFS-ScheduleChanges v3.1 proposal for an official way to add or modify trips.