Coroutines concurence query multiple firestore document in Kotlin

CoroutinesConcurence.kt

    private fun showMultiStableInfo(stableKeys: Set<Any?>) {
        val scope = CoroutineScope(Dispatchers.Default)
        scope.launch {

            var stables = arrayListOf<Stable>()
            stableKeys.forEach { key ->
                key?.let { stableID ->
                    val job = CoroutineScope(Dispatchers.Default).async {
                        suspendCoroutine<Stable?> { cont ->
                            myRef.child("stables").child(stableID as String).addListenerForSingleValueEvent(object : ValueEventListener {
                                override fun onDataChange(snapshot: DataSnapshot) {
                                    val stable = snapshot.getValue(Stable::class.java)
                                    cont.resume(stable)
                                }

                                override fun onCancelled(error: DatabaseError) {
                                }
                            })
                        }
                    }
                    val stable = job.await()
                    stable?.let {
                        stables.add(stable)
                    }
                }
            }
            activity?.runOnUiThread {
                // do something

            }

        }
    }