Proposal for specifying the message key with AMQP group-id

[ppatierno]

Currently the message key is specified through the custom annotation :

x-opt-bridge.key

We could use the system property group-id for that. Leaving the x-opt-bridge.partition custom annotation for specifying partition.

So ...

for key : group-id is used or if it's not specified, the x-opt-bridge.key is used for partition : it's possible only using x-opt-bridge.partition