OpenJDK 11 is now the default Java package in Ubuntu 18.04 LTS, replacing OpenJDK 10, the previously supported rapid release version and original package default for Ubuntu 18.04. This OpenJDK package is covered by the standard, LTS upstream security support and will also be the default package for the upcoming Ubuntu 19.04 release.
Version 11 is the latest Long Term Support (LTS) version of the open-source implementation of the Java Platform, Standard Edition (Java SE). It incorporates key security improvements, including an update to the latest Transport Layer Security (TLS) version, TLS 1.3, and the implementation of ChaCha20-Poly1305 cryptographic algorithms, a new stream cipher that can replace the less secure RC4.
This OpenJDK upgrade also includes fixes for build failures, JavaDoc tool improvements and the removal of deprecated APIs like Pack200, a compression scheme no longer needed for JAR files.
OpenJDK 8, the former upstream LTS release, is still available and has been moved into the community-supported universe repository. Security updates for OpenJDK 8 will be provided until April 2021 for both Ubuntu 16.04 LTS and 18.04 LTS.