channelFlowCallback  
  inline suspend fun ChimeSdkMessagingClient.channelFlowCallback(crossinline block: ChannelFlowCallbackRequest.Builder.() -> Unit): ChannelFlowCallbackResponse
Calls back Amazon Chime SDK messaging with a processing response message. This should be invoked from the processor Lambda. This is a developer API.
You can return one of the following processing responses:
- Update message content or metadata 
- Deny a message 
- Make no changes to the message