Changelog for 2.217

What's new in 2.217 (2020-01-23)

• Fix localized versions to no longer report can't parse argument number: changelog.url (regression in 2.214). (issue 60822)
• Jenkins 2.212+ failed to load certain injected fields such as used by the Bitbucket Server Integration plugin. (issue 60816)
• Add experimental WebSocket support. (JEP-222, blog post)
• Upgrade Jetty from 9.4.22.v20191022 to 9.4.25.v20191220. (Jetty 9.4.23 release notes, Jetty 9.4.24 release notes, Jetty 9.4.25 release notes)
• Upgrade to Remoting 4.0. (Remoting 4.0 release notes)
• Prevent inaccurate warnings about missing classes on Java 11 triggered by JavaMelody when Monitoring Plugin is installed. (issue 60725)
• Fix java version check for AdoptOpenJDK 11. (issue 60678)
• Internal: frontend toolchain upgraded to use webpack. Enabled babel to transpile certain JS modules. (issue 60734)
• Developer: Update access-modifier to allow plugins to use suppressions (pull 4441)