Currently, synchronous was only honoured by Camel itself to execute the route synchronously.
We should also honour it by acting synchronously when sending back the answer at the end of the route execution.
Backported to 4.3.x https://github.com/petalslink/petals-se-camel/commit/9a3edfaa48c72d5095cd8dbc42d65c7452d741b9
Backported to 4.3.x https://github.com/petalslink/petals-se-camel/commit/9a3edfaa48c72d5095cd8dbc42d65c7452d741b9