Hi,

It is not possible to run the 21w37a snapshot on an alternate JVM (OpenJ9) that does not have the Java Flight Recorder included, as there seems to be a hard dependency. This was not the case in previous 1.17 versions.

Steps to reproduce:
1) Install OpenJ9 JVM
2) Start the 21w37a snapshot
3) The server does not start

Exception:

Exception in thread "main" java.lang.NoClassDefFoundError: jdk.jfr.FlightRecorder
at dn.<init>(SourceFile:208)
at xn.<init>(SourceFile:39)
at xn.a(SourceFile:88)
at net.minecraft.server.Main.main(SourceFile:162)
Caused by: java.lang.ClassNotFoundException: jdk.jfr.FlightRecorder
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:822)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:1106)
... 4 more

No crash report is created.