Called after two forces have been merged using game.merge_forces().
The source force is invalidated before this event is called and the name can be re-used in this event if desired.
source_name: string — The force destroyed.source_index: uint32 — The index of the destroyed force.destination: LuaForce — The force entities where reassigned to.name: defines.events — Identifier of the eventtick: uint32 — Tick the event was generated.