Class accessibility problems when launching MC1.17.x and MC1.18.x

[Elec332]

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

When attempting to runClient/runServer (both) a project for MC 1.17.1 Forge 37.1.1 using java 16 start will always fail because of accessibility issues with cpw.mods.bootstraplauncher.BootstrapLauncher. Example output:

> Task :runServer FAILED
Slime Launcher 0.1.8
Checking assets
Looking for main class: cpw.mods.bootstraplauncher.BootstrapLauncher
4 actionable tasks: 3 executed, 1 up-to-date
Configuration cache entry stored.
Exception in thread "main" java.lang.IllegalStateException: Could not find main class!
	at net.minecraftforge.launcher.Main.run(Main.java:125)
	at net.minecraftforge.launcher.Main.main(Main.java:34)
Caused by: java.lang.IllegalAccessException: symbolic reference class is not accessible: class cpw.mods.bootstraplauncher.BootstrapLauncher, from public Lookup
	at java.base/java.lang.invoke.MemberName.makeAccessException(MemberName.java:957)
	at java.base/java.lang.invoke.MethodHandles$Lookup.checkSymbolicClass(MethodHandles.java:3675)
	at java.base/java.lang.invoke.MethodHandles$Lookup.resolveOrFail(MethodHandles.java:3647)
	at java.base/java.lang.invoke.MethodHandles$Lookup.findStatic(MethodHandles.java:2595)
	at net.minecraftforge.launcher.Main.run(Main.java:123)
	... 1 more
Something went wrong! Here is some debug info.
Args: [--main, cpw.mods.bootstraplauncher.BootstrapLauncher, --cache, E:\Programming\.environment\.gradle\caches\minecraftforge\forgegradle\slime-launcher\cache\net\minecraftforge\forge\1.17.1-37.1.1, --metadata, E:\Programming\Local\Java\forge-FG7-test\.gradle\mavenizer\repo\net\minecraftforge\forge\1.17.1-37.1.1\forge-1.17.1-37.1.1-metadata.zip, --, --launchTarget, forgeserveruserdev, --gameDir, ., --fml.forgeVersion, 37.1.1, --fml.mcVersion, 1.17.1, --fml.forgeGroup, net.minecraftforge, --fml.mcpVersion, 20210706.113038, --nogui]
JVM Args: [-p, E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\cpw.mods\bootstraplauncher\0.1.17\899fb8e3912bb7d14a6f9611de117f77db710ec3\bootstraplauncher-0.1.17.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\cpw.mods\securejarhandler\0.9.54\24b670f2c026ec9777e64a2c2126ebc8635dbe8d\securejarhandler-0.9.54.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\org.ow2.asm\asm-commons\9.1\8b971b182eb5cf100b9e8d4119152d83e00e0fdd\asm-commons-9.1.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\org.ow2.asm\asm-util\9.1\36464a45d871779f3383a8a9aba2b26562a86729\asm-util-9.1.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\org.ow2.asm\asm-analysis\9.1\4f61b83b81d8b659958f4bcc48907e93ecea55a0\asm-analysis-9.1.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\org.ow2.asm\asm-tree\9.1\c333f2a855069cb8eb17a40a3eb8b1b67755d0eb\asm-tree-9.1.jar;E:\Programming\.environment\.gradle\caches\modules-2\files-2.1\org.ow2.asm\asm\9.1\a99500cf6eea30535eeac6be73899d048f8d12a8\asm-9.1.jar, --add-modules, ALL-MODULE-PATH, --add-opens, java.base/java.util.jar=cpw.mods.securejarhandler, --add-exports, java.base/sun.security.util=cpw.mods.securejarhandler, --add-exports, jdk.naming.dns/com.sun.jndi.dns=java.naming]
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_1.17.1
System:
	legacyClassPath.file: E:\Programming\Local\Java\forge-FG7-test\build\minecraftforge\forgegradle\slime-launcher\cache\net\minecraftforge\forge\1.17.1-37.1.1\minecraft_classpath.txt
	ignoreList: bootstraplauncher,securejarhandler,asm-commons,asm-util,asm-analysis,asm-tree,asm,client-extra,fmlcore,javafmllanguage,mclanguage,forge-
	eventbus.api.strictRuntimeChecks: true
	mergeModules: jna-5.8.0.jar,jna-platform-58.0.jar,java-objc-bridge-1.0.0.jar
	forge.enabledGameTestNamespaces: examplemod
Options: SlimeLauncherOptionsImpl{name=server, mainClass=cpw.mods.bootstraplauncher.BootstrapLauncher, args=[--launchTarget, forgeserveruserdev, --gameDir, ., --fml.forgeVersion, 37.1.1, --fml.mcVersion, 1.17.1, --fml.forgeGroup, net.minecraftforge, --fml.mcpVersion, 20210706.113038, --nogui], jvmArgs=[-p, {modules}, --add-modules, ALL-MODULE-PATH, --add-opens, java.base/java.util.jar=cpw.mods.securejarhandler, --add-exports, java.base/sun.security.util=cpw.mods.securejarhandler, --add-exports, jdk.naming.dns/com.sun.jndi.dns=java.naming], classpath=[], minHeapSize=null, maxHeapSize=null, systemProperties={legacyClassPath.file={minecraft_classpath_file}, ignoreList=bootstraplauncher,securejarhandler,asm-commons,asm-util,asm-analysis,asm-tree,asm,client-extra,fmlcore,javafmllanguage,mclanguage,forge-, mergeModules=jna-5.8.0.jar,jna-platform-58.0.jar,java-objc-bridge-1.0.0.jar, eventbus.api.strictRuntimeChecks=true, forge.enabledGameTestNamespaces=examplemod}, environment={MOD_CLASSES={source_roots}, MCP_MAPPINGS={mcp_mappings}}, workingDir=E:\Programming\Local\Java\forge-FG7-test\run, client=false}

[LexManos]

Unfortunately due to java's module system, things are locked down even tho they shouldn't be.
You can address this by adding jvmArgs '--add-opens', 'cpw.mods.bootstraplauncher/cpw.mods.bootstraplauncher=ALL-UNNAMED' to your run config.
From my tests this should only be needed on 1.17/1.18
I need to decide the best place to add this hack. Probably in mavenizer, just need to find a simple way to do it without breakaing other builds.