Thanks for the lookout!
These things are good to be aware of, although I don’t think Processing is in any danger of migrating to Java 11 anytime soon.
Processing 3 uses Java 8 (but does not support all Java 8 language features). […] there are no plans to support Java 9 or 10. The first version we might use is Java 11, a “long term support” release, scheduled for September 2018. However, without anyone contributing their time to rework the code for Java 9/10/11, we’ll be using Java 8 for the foreseeable future.
Supported Platforms · processing/processing Wiki · GitHub
Write now Processing syntax supports most of 7 and some 8 language features running backed by 8.