Optimise path filter in mod loading (#9711)

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/AbstractModProvider.java

@@ -38,7 +38,7 @@ public abstract class AbstractModProvider implements IModProvider
         var sj = SecureJar.from(
                 Manifest::new,
                 jar -> jar.moduleDataProvider().findFile(MODS_TOML).isPresent() ? mjm : JarMetadata.from(jar, path),
-                (root, p) -> true,
+                null,
                 path
         );
 

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ExplodedDirectoryLocator.java

@@ -34,7 +34,7 @@ public class ExplodedDirectoryLocator implements IModLocator {
         explodedMods.forEach(explodedMod ->
                 ModJarMetadata.buildFile(this,
                         jar->jar.moduleDataProvider().findFile("/META-INF/mods.toml").isPresent(),
-                        (a,b) -> true,
+                        null,
                         explodedMod.paths().toArray(Path[]::new))
                 .ifPresentOrElse(f->mods.put(explodedMod, f), () -> LOGGER.warn(LogMarkers.LOADING, "Failed to find exploded resource mods.toml in directory {}", explodedMod.paths().get(0).toString())));
         return mods.values().stream().map(mf->new IModLocator.ModFileOrException(mf, null)).toList();

fmlloader/src/main/java/net/minecraftforge/fml/loading/moddiscovery/ModJarMetadata.java

@@ -31,7 +31,7 @@ public final class ModJarMetadata implements JarMetadata {
     // TODO: Remove helper functions to cleanup api
     @Deprecated(forRemoval = true, since="1.18")
     static IModFile buildFile(IModLocator locator, Path... files) {
-        return buildFile(locator, j->true, (a,b) -> true, files).orElseThrow(()->new IllegalArgumentException("Failed to find valid JAR file"));
+        return buildFile(locator, j->true, null, files).orElseThrow(()->new IllegalArgumentException("Failed to find valid JAR file"));
     }
 
     // TODO: Remove helper functions to cleanup api

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/CommonClientLaunchHandler.java

@@ -43,7 +43,7 @@ public abstract class CommonClientLaunchHandler extends CommonLaunchHandler {
         var lowcodelang = LibraryFinder.findPathForMaven(vers.forgeGroup(), "lowcodelanguage", "", "", vers.mcAndForgeVersion());
         var mclang = LibraryFinder.findPathForMaven(vers.forgeGroup(), "mclanguage", "", "", vers.mcAndForgeVersion());
 
-        return new LocatedPaths(mcstream.build().toList(), (a,b) -> true, modstream.build().toList(), List.of(fmlcore, javafmllang, lowcodelang, mclang));
+        return new LocatedPaths(mcstream.build().toList(), null, modstream.build().toList(), List.of(fmlcore, javafmllang, lowcodelang, mclang));
     }
 
     protected abstract void processMCStream(VersionInfo versionInfo, Stream.Builder<Path> mc, Stream.Builder<List<Path>> mods);

fmlloader/src/main/java/net/minecraftforge/fml/loading/targets/CommonServerLaunchHandler.java

@@ -42,13 +42,21 @@ public abstract class CommonServerLaunchHandler extends CommonLaunchHandler {
                       !path.startsWith("META-INF/"));
             }, mcextra
         );
+
+        // Todo in 1.20.2: Change the default filter to null instead of always true.
         BiPredicate<String, String> filter = (path, base) -> true;
+        final BiPredicate<String, String> alwaysTrueFilter = filter;
 
         var mcstream = Stream.<Path>builder().add(mc).add(mcextra_filtered.getRootPath());
         var modstream = Stream.<List<Path>>builder();
 
         filter = processMCStream(vers, mcstream, filter, modstream);
 
+        // Ensure backwards compatibility if anything overrides processMCStream()
+        // and expects the default always true filter by only changing it to null afterwards if left unchanged.
+        if (filter == alwaysTrueFilter)
+            filter = null;
+
         var fmlcore = LibraryFinder.findPathForMaven(vers.forgeGroup(), "fmlcore", "", "", vers.mcAndForgeVersion());
         var javafmllang = LibraryFinder.findPathForMaven(vers.forgeGroup(), "javafmllanguage", "", "", vers.mcAndForgeVersion());
         var lowcodelang = LibraryFinder.findPathForMaven(vers.forgeGroup(), "lowcodelanguage", "", "", vers.mcAndForgeVersion());