I tried to implement combineLatest for kotlin channels with corutines

kotlin_channels_combineLatest.kt

import kotlinx.coroutines.experimental.channels.Channel
import kotlinx.coroutines.experimental.delay
import kotlinx.coroutines.experimental.launch
import kotlinx.coroutines.experimental.runBlocking
import kotlinx.coroutines.experimental.selects.select
import java.util.*

/*
 * Combine multiple channels into one `output` channel.
 * Output contains last known data from all channels and sends data on every change.
 * Output is closed when any other channel closes first.
 */
suspend fun <T> combineLatest(channels: List<Channel<T>>) : Channel<List<T?>> {
    val state = Collections.synchronizedList(mutableListOf<T?>())
    for (i in 0..channels.size - 1) { state.add(i, null) }
    val output = Channel<List<T?>>()
    for (channel in channels) {
        launch {
            var quit = false
            do {
                val value = channel.receiveOrNull()
                if (value == null) {
                    output.close()
                    quit = true
                    return@launch
                } else {
                    state.set(channels.indexOf(channel), value)
                    output.offer(state)
                }
            } while (!quit)
        }
    }
    return output
}

fun main(args: Array<String>) = runBlocking<Unit> {

    val channel = Channel<Int>()
    val producer = launch {
        for (x in 1..15) {
            delay(1000)
            println("0 ==> " + x)
            channel.send(x)
        }
        channel.close() // we're done sending
    }

    val channel2 = Channel<Int>()
    val producer2 = launch {
        for (x in 1..15) {
            delay(1100)
            println("1 ==> " + x)
            channel2.send(x)
        }
        channel.close() // we're done sending
    }

    val consumer = launch {
        val output = combineLatest(listOf(channel, channel2))
        do {
            // delay(2000)
            val values = output.receiveOrNull()
            println(values)
        } while (!output.isClosedForReceive)
    }

    consumer.join()
}