Replace single per-user API token with new system of multiple, revocable, unrecoverable API tokens with usage tracking.
(issue 32442, issue 32776, blog post)
Dynamically loaded plugins now have any PeriodicWork/AperiodicWork extensions scheduled.
(issue 28683)
Upgrade Bytecode Compatibility Transformer from 1.8 to 2.0-beta-2, upgrading ASM from 5.0.1 to 6.2 to improve support of Java 9+ runtimes.
(issue 51837, supported Java versions)
Upgrade Remoting from 3.21 to 3.22 to have agents check availability of the controller's TCP Agent Listener port when connecting over TCP.
(issue 51818, Remoting 3.22 changelog)
Developer API: Remoting 3.22 now offers a new Channel#readFrom(Channel, byte[]) method for a standardized command deserialization from the channel.
(issue 51841)