adoptedBy method
The child's own word on who may adopt it.
Empty here: JobContextBase.startChild has already checked that the child is a job of this core.
To refuse, throw — an ArgumentError for a parent that may not have this
child, a StateError for a child that is spoken for. The error comes out
of the call that asked — for JobContext.runAll, once the branches it
already started have stopped — before the child has a parent, and the
child stays created.
See One loop, and no other way to start on the engine page.
Implementation
@visibleForOverriding
void adoptedBy(JobContextBase parent) {}