After 6 months you move to the next release, just like most people do with libraries, JDK is just another library, no need to worry about upgrading, just do normal regression like with upgrades of other libs. There are no major releases of JDK, all current ones are minor ones - just like in case of JDK 8 you got new features in minor releases (e.g. change in changing of toString, added classes in standard library - no one was worried about that then)
And BTW. Azul MTS want's to have a word with you: https://www.azul.com/products/azul-support-roadmap/
e.g. JDK 13 and 15 do get builds.