Queue messages get their id from body of message.

I am not sure if this is intentional but if a message contains an "Id" field it seems to be used as the `id` property in `QueueMessage`. I assume that this has something to do with how the contents of `trigger_metadata` are set (I am unable to identify the origin of the argument). I assume this because of how it is being extacted in `QueueMessageInConverter` and the fact that my messages arrive with the same `body['Id']` and `msg.id`.

Maybe I am completly wrong but I am curious if this is intentional or aviodable somehow, if not I would like to open a discussion about it.

I personally did not expect this behaviour and it required a ugly workaround.