Cancels all children jobs of this coroutine using Job.cancel for all of them with an optional cancellation cause. Unlike Job.cancel on this job as a whole, the state of this job itself is not affected.
Cancels all children of the Job in this context, without touching the state of this job itself with an optional cancellation cause. See Job.cancel. It does not do anything if there is no job in the context or it has no children.