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Javalin fails on Java 19 without --enable-preview

See original GitHub issue

Actual behavior (the bug) I ran brew upgrade which gave me Java 19. When I booted up my Javalin app I saw this exception:

20220928 17:09:36.260 [main] INFO  / io.javalin.Javalin - Starting Javalin ...
20220928 17:09:36.271 [main] INFO  / io.javalin.Javalin - You are running Javalin 4.6.4 (released July 8, 2022).
20220928 17:09:36.301 [main] INFO  / io.javalin.Javalin - Loom is available, using Virtual ThreadPool... Neat!
20220928 17:09:36.303 [main] ERROR / io.javalin.Javalin - Failed to start Javalin
20220928 17:09:36.305 [main] INFO  / io.javalin.Javalin - Loom is available, using Virtual ThreadPool... Neat!
Exception in thread "main" java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:119)
	at java.base/java.lang.reflect.Method.invoke(Method.java:578)
	at io.javalin.core.LoomUtil.getExecutorService(LoomUtil.kt:22)
	at io.javalin.jetty.LoomThreadPool.<init>(JettyUtil.kt:90)
	at io.javalin.jetty.JettyUtil.defaultThreadPool(JettyUtil.kt:28)
	at io.javalin.jetty.JettyUtil.getOrDefault(JettyUtil.kt:20)
	at io.javalin.jetty.JettyServer.server(JettyServer.kt:34)
	at io.javalin.Javalin.start(Javalin.java:180)
	at io.javalin.Javalin.start(Javalin.java:148)
	[...]
Caused by: java.lang.UnsupportedOperationException: Preview Features not enabled, need to run with --enable-preview
	at java.base/jdk.internal.misc.PreviewFeatures.ensureEnabled(PreviewFeatures.java:49)
	at java.base/java.lang.Thread.ofVirtual(Thread.java:833)
	at java.base/java.util.concurrent.Executors.newVirtualThreadPerTaskExecutor(Executors.java:274)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
	... 10 more

Expected behavior Javalin should work (without virtual threadpools) on Java 19 without loom enabled.

To Reproduce Run Javalin with Java 19 and without the --enable-preview flag.

Additional context To fix it, in IntelliJ I edited my run configuration, and added --enable-preview to the VM Options section.