Forge 1.20.1 install fails: NoSuchMethodError ClientInstall.run(File, Predicate, File)

[Narcissus-tazetta]

Summary

Running the action against mc: 1.20.1, modloader: forge fails during the Forge client install step with:

java.lang.NoSuchMethodError: 'boolean net.minecraftforge.installer.actions.ClientInstall.run(java.io.File, java.util.function.Predicate, java.io.File)'
	at net.kunmc.lab.forgecli.impl.ClientInstall.run(ClientInstall.java:19)
	at net.kunmc.lab.forgecli.InstallerUtil.runClientInstall(InstallerUtil.java:29)
	at net.kunmc.lab.forgecli.Installer.installPost1_13(Installer.java:42)
	at net.kunmc.lab.forgecli.Installer.install(Installer.java:24)

This happens right after Installing Forge 1.20.1-47.4.23.

Root cause (verified with javap)

net.kunmc.lab.forgecli.impl.ClientInstall calls a 3-argument overload
net.minecraftforge.installer.actions.ClientInstall.run(File, Predicate, File), but the real
Forge installer jar for 1.20.1 only ever exposes a 2-argument run(File, File). I checked this
directly against the actual Forge installer jars for every 1.20.1 build from 47.1.0 through the
current latest 47.4.23 (net.minecraftforge:forge:1.20.1-<version>:installer) — all of them have:

public boolean run(java.io.File, java.io.File) throws net.minecraftforge.installer.actions.ActionCanceledException;

So this isn't a matter of picking a different/newer/older Forge 1.20.1 patch version — the 3-arg
signature forgecli expects has never existed on any 1.20.1 Forge installer. It looks like
forgecli's ClientInstall wrapper was built against a newer Forge installer API (with a
Predicate argument, presumably for library filtering) that only exists for later Minecraft
versions, and no longer supports the old-style 1.20.1-era 2-arg ClientInstall.run.

Environment

• Action version: headlesshq/mc-runtime-test@4.5.1
• Inputs: mc: 1.20.1, modloader: forge, java: 21
• CI run: https://github.com/Narcissus-tazetta/XaeroNav/actions/runs/34601191824/job/103274922737

Expected

Forge 1.20.1 client install succeeds (or the README's Forge/1.20.1 support row is corrected if this
combination is actually unsupported).