I have just released what will probably be the final version of PiCrate for rasbian stretch on RaspberryPI3+. It is specifically designed to use the Oracle jdk8 that comes with the stretch distribution, here is a snapshot of sketch running from the Geany IDE:-
I have already created a jdk11 branch to support Buster. Currently you need to install OpenJDK11 yourself:-
apt-get install openjdk-11-jdk
Because of this change, the next release of PiCrate will be version 2, currently OpenJDK11 is not as performant as the Oracle java.
However currently you may prefer to use openjdk-8-jdk on Buster since it seem to outperform OpenJDK11 and isn’t noisy about reflective access.