Fix hang on System.exit() due to shutdown hook waiting for server stop

Author: NotStirred

src/integrationTest/java/io/github/opencubicchunks/cubicchunks/test/mixin/server/MixinMain.java

@@ -0,0 +1,14 @@
+package io.github.opencubicchunks.cubicchunks.test.mixin.server;
+
+import net.minecraft.server.Main;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+@Mixin(Main.class)
+public class MixinMain {
+    @Redirect(method = "main", at = @At(value = "INVOKE", target = "Ljava/lang/Runtime;addShutdownHook(Ljava/lang/Thread;)V"), remap = false)
+    private static void noShutdownHook(Runtime instance, Thread hook) {
+        // Do nothing
+    }
+}