runServer is missing launch handler on classpath <=MC1.16.5

Reproduce the failure with the MDKExamples obfuscation/fg7/build.gradle setup and the runServer entry point for Minecraft 1.16.5 on Java 8. Trace how SlimeLauncher assembles the classpath before net.minecraftforge.userdev.LaunchTesting starts; done means the fmluserdevserver launch handler is found and runServer proceeds past startup.

On a clean project as per https://github.com/MinecraftForge/MDKExamples/blob/master/obfuscation/fg7/build.gradle

When attempting to runServer a project for any MC version <= 1.16.5 (e.g. MC 1.16.5 Forge 36.2.42) using java 8 it appears that the launch handler is not on the classpath. Example output:

> Task :runServer FAILED
Slime Launcher setup is up-to-date, took 325ms
Launching using main class: net.minecraftforge.userdev.LaunchTesting
2026-03-05 00:06:13,140 main WARN Advanced terminal features are not available in this environment
[00:06:13] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--nogui, --gameDir, ., --launchTarget, fmluserdevserver, --fml.mcpVersion, 20210115.111550, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge, --fml.forgeVersion, 36.2.42]
[00:06:13] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.1.3+8.1.3+main-8.1.x.c94d18ec starting: java version 1.8.0_482 by Temurin
[00:06:13] [main/INFO] [ne.mi.fm.lo.FixSSL/CORE]: Added Lets Encrypt root certificates as additional trust
[00:06:13] [main/INFO] [mixin/]: SpongePowered MIXIN Subsystem Version=0.8.4 Source=file:/E:/Programming/.environment/.gradle/caches/modules-2/files-2.1/org.spongepowered/mixin/0.8.4/4ec7d77d9ab32596ca0b78bb123956734767e3a/mixin-0.8.4.jar Service=ModLauncher Env=SERVER
[00:06:13] [main/FATAL] [ne.mi.fm.lo.FMLLoader/CORE]: Missing LaunchHandler fmluserdevserver, cannot continue
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: java.lang.RuntimeException: Missing launch handler
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.fml.loading.FMLLoader.setupLaunchHandler(FMLLoader.java:160)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.fml.loading.FMLServiceProvider.initialize(FMLServiceProvider.java:80)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.TransformationServiceDecorator.onInitialize(TransformationServiceDecorator.java:68)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.TransformationServicesHandler.lambda$initialiseTransformationServices$7(TransformationServicesHandler.java:107)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at java.util.HashMap$Values.forEach(HashMap.java:982)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.TransformationServicesHandler.initialiseTransformationServices(TransformationServicesHandler.java:107)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.TransformationServicesHandler.initializeTransformationServices(TransformationServicesHandler.java:59)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.Launcher.run(Launcher.java:76)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at cpw.mods.modlauncher.Launcher.main(Launcher.java:66)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.userdev.LaunchTesting.main(LaunchTesting.java:94)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.launcher.Main$Launcher.run(Main.java:152)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.launcher.Main$Launcher.access$000(Main.java:138)
[00:06:13] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1052]: 	at net.minecraftforge.launcher.Main.main(Main.java:49)
4 actionable tasks: 1 executed, 3 up-to-date
Configuration cache entry reused.
Exception in thread "main" Something went wrong! Here is some debug info.
Args: [--main, net.minecraftforge.userdev.LaunchTesting, --cache, E:\Programming\.environment\.gradle\caches\minecraftforge\forgegradle\slime-launcher\cache\net\minecraftforge\forge\1.16.5-36.2.42, --metadata, E:\Programming\Local\Java\forge-FG7-test\.gradle\mavenizer\repo\net\minecraftforge\forge\1.16.5-36.2.42\forge-1.16.5-36.2.42-metadata.zip, --, --nogui]
JVM Args: [-XX:+IgnoreUnrecognizedVMOptions, --add-exports=java.base/sun.security.util=ALL-UNNAMED, --add-exports=jdk.naming.dns/com.sun.jndi.dns=java.naming, --add-opens=java.base/java.util.jar=ALL-UNNAMED]
Environment:
	MOD_CLASSES: E:\Programming\Local\Java\forge-FG7-test\build\sourceSets\main;E:\Programming\Local\Java\forge-FG7-test\build\sourceSets\main
	MCP_MAPPINGS: official_1.16.5
	MCP_VERSION: 20210115.111550
	FORGE_VERSION: 36.2.42
	FORGE_GROUP: net.minecraftforge
	target: fmluserdevserver
	MC_VERSION: 1.16.5
System:
	eventbus.api.strictRuntimeChecks: true
	forge.enabledGameTestNamespaces: examplemod
Options: SlimeLauncherOptionsImpl{name=server, mainClass=net.minecraftforge.userdev.LaunchTesting, args=[--nogui], jvmArgs=[-XX:+IgnoreUnrecognizedVMOptions, --add-exports=java.base/sun.security.util=ALL-UNNAMED, --add-exports=jdk.naming.dns/com.sun.jndi.dns=java.naming, --add-opens=java.base/java.util.jar=ALL-UNNAMED], classpath=[], minHeapSize=null, maxHeapSize=null, systemProperties={eventbus.api.strictRuntimeChecks=true, forge.enabledGameTestNamespaces=examplemod}, environment={MOD_CLASSES={source_roots}, MCP_MAPPINGS={mcp_mappings}, MCP_VERSION=20210115.111550, FORGE_VERSION=36.2.42, FORGE_GROUP=net.minecraftforge, target=fmluserdevserver, MC_VERSION=1.16.5}, workingDir=E:\Programming\Local\Java\forge-FG7-test\run, client=false}