Message Transformation shape

I recently used a message transformation shape in one of my orchestration.

The orchestration initialized with receiving a message, which was converted to a webservice request and the response from webservice was then need to be transformed to response message.

The final response message was made up of 2 source messages (1 received in the beginning and 1 received as response from webservice)

I was required to copy the context properties of the very first message received to the newly created message (post transformation). In order to achieve the same, I followed the simple method i.e., DestinationMsg(*) = SourceMsg(*).

For some reason I later commented this line and still could find the context properties on the destination message intact. What I can assume is, it's the message transformation shape which is in some way copying the context properties even ... strange, but it is true.