Alternative implementation of HandlerContext for Android that continues coroutine with CancellationException when the job is complete (i.e. it was cancelled from outside)

CancellableHandlerContext.kt

public class CancellableHandlerContext(
    private val handler: Handler
) : AbstractCoroutineContextElement(ContinuationInterceptor), ContinuationInterceptor, Delay
{
    override fun <T> interceptContinuation(continuation: Continuation<T>): Continuation<T> =
        DispatchedContinuation(continuation)

    override fun scheduleResumeAfterDelay(time: Long, unit: TimeUnit, continuation: CancellableContinuation<Unit>) {
        handler.postDelayed(object : ResumeTask<Unit>(continuation) {
            override fun resume() = continuation.resume(Unit)
        }, unit.toMillis(time))
    }

    override fun invokeOnTimeout(time: Long, unit: TimeUnit, block: Runnable): DisposableHandle {
        handler.postDelayed(block, unit.toMillis(time))
        return object : DisposableHandle {
            override fun dispose() {
                handler.removeCallbacks(block)
            }
        }
    }

    private abstract inner class ResumeTask<in T>(val continuation: Continuation<T>) : Runnable {
        override fun run() {
            if (continuation.context[Job]?.isCompleted == true)
                continuation.resumeWithException(CancellationException("Cancelled")) else
                resume()
        }

        abstract fun resume()
    }

    private inner class DispatchedContinuation<T>(val delegate: Continuation<T>) : Continuation<T> {
        override val context: CoroutineContext = delegate.context

        override fun resume(value: T) {
            handler.post(object : ResumeTask<T>(delegate) {
                override fun resume() = continuation.resume(value)
            })
        }

        override fun resumeWithException(exception: Throwable) {
            handler.post(object : ResumeTask<T>(delegate) {
                override fun resume() = continuation.resumeWithException(exception)
            })
        }
    }
}