Wish list: Decision and loop in message construct
For instacne - a decision shape could be very useful.
For instance - imagine you construct a multi-part message where one part is always a result of a map and the other parts are assignments of other messages, only that the source message you need to use depends on something...
Another, even more common scenario is when you are constructing a message and then assign some context properties. but you need to assign different values, possibly to different properties. again - based on something. doesnt matter what.
There are easy enough ways around that, but not being able to have an if-then-else
logic in the construct shape makes the process quite big and ugly (and wasteful)
To push it a bit I even believe it would be quite useful to use a loop in a construct shape. for instance for a message aggregation. but that might be too much to ask for, I admit.