this.executorServiceOrNull = executorService
  }

  internal fun enqueue(call: AsyncCall) {
    promoteAndExecute(enqueuedCall = call)
  }

  private fun findExistingCallWithHost(host: String): AsyncCall? {
    for (existingCall in runningAsyncCalls) {
      if (existingCall.host == host) return existingCall
    }
    for (existingCall in readyAsyncCalls) {