Java 9 and 10 were the first limited-support "intermediate" releases. 10 was released late March 2018 and received its last update mid-July 2018. Because those

Java 9 and 10 were the first limited-support "intermediate" releases. 10 was released late March 2018 and received its last update mid-July 2018. Because those versions only had 6 months of support planned, very few people moved old projects to them, and few if any Linux distributions packaged them as part of their LTS releases. This left Ubuntu in an awkward position with their 18.04 LTS release. Java 8 was at that point 4 years old and heading towards EOL, Java 10 had just been released but would only have 6 months of support, and Java 11 wasn't to be released until September. The compromise they came up with was to ship a package called "openjdk-11" which actually contained Java 10, with plans to update it to Java 11 when that was released, in the hopes that the two would be relatively similar. It ended up taking around 6 months to finish testing 11 after its release, so it ended up being March 2019, nearly a year after the release of 18.04, that they finally put Java 11 in their Java 11 package. I'm not sure this answers your question, but that was the recent Java release timeline and how Ubuntu chose to deal with it.