The focus of this minor release has been (again :-) )on stabilizing and cleanup the existing functionality of 2.1.0 and fixing bugs.
Work on providing a redesigned proxy could still not be finished for this release, but a preview is available as californium-proxy2 and cf-proxy2. The APIs of the new proxy are under development and not stable.
This release is intended to be the base for the leshan 1.0 release. We therefore decided to postpone the fix for resending the handshakemode on retransmission, details see discussion in PR 1246