Java 9 was released end of September 2017... That's less than 1.5 years to migrate all your apps (possible many hundreds) from Java 8 to Java 9. Way too short.

In fact, Java 9 is already out of support (since last month). The next viable Java version after Java 8 is Java 11, which is an LTS version. Java 11 will come out around September this year. So in reality, this means organizations have a couple months to migrate everything from Java 8 to Java 11. Laughable.