To use loom you need java 19 with --enable-preview in the run configuration.

sdk install java 19.0.2-amzn

At the moment of the creation of this project gradle does not support java 19.

Loom is for generating non-blocking virtual threads at the JVM level. Running the main example will give:

start ...
wait for threads execution ...
thread over after 100 ms
thread over after 110 ms
over