Ubuntu 18.04 has shifted from OpenJDK 10 to 11 since OpenJDK 11 is a long-term support release and thus better aligned with Ubuntu 18.04 being an LTS release itself than continuing to use OpenJDK 10 or the latest 12 release. This shouldn't come as a surprise as February of last year we wrote how Ubuntu 18.04 LTS would likely ship with OpenJDK 10 and then transition to 11 when ready.
Details on this default Java shift can be found via this Ubuntu blog post from Friday.
Meanwhile, Red Hat has taken over maintenance of OpenJDK 8 and OpenJDK 11 from Oracle.
与此同时，Red Hat已经从Oracle接管了OpenJDK 8和OpenJDK 11的维护。
I did use this opportunity to run some OpenJDK 8/11/12 benchmarks on Ubuntu 18.04 LTS over Easter weekend. On the Core i9 7980XE EE box I ran benchmarks using Ubuntu's OpenJDK 8 and 11 LTS packaging and then OpenJDK 12 Linux binaries from upstream.