The focus of this minor release has been on stabilizing and cleanup the existing functionality of 2.0.0 and fixing bugs.
The DTLS session management is improved by a "default handshake mode", which provides new flexibility, and by a bugfix for using a message based handshake mode for a blockwise transfer.
x509 now supports a configurable key usage check and the certificates path may now be truncated at a CA either on the client or server side, also configurable.
Work on providing a redesigned proxy could 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.
The client-side support for RFC7252 compliant support of proxies is implemented, but will slightly change with the next major version, when the deprecated methods will be removed.