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

Reproduce the failure with the FG7 example in build.gradle by running runClient and runServer for Minecraft 1.17.1. Start with net.minecraftforge.launcher.Main at the lookup shown in Main.java:123, then inspect how BootstrapLauncher is resolved with the module-path arguments. Done means both launch tasks find the main class without the accessibility exception.

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}