Remove duplicate list held by DebugLevelSource

src/main/java/org/embeddedt/modernfix/common/mixin/perf/forge_registry_alloc/DebugLevelSourceMixin.java

@@ -0,0 +1,38 @@
+package org.embeddedt.modernfix.common.mixin.perf.forge_registry_alloc;
+
+import net.minecraft.world.level.levelgen.DebugLevelSource;
+import net.minecraftforge.registries.GameData;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+import java.util.AbstractList;
+import java.util.stream.Collector;
+import java.util.stream.Stream;
+
+@Mixin(DebugLevelSource.class)
+public class DebugLevelSourceMixin {
+    /**
+     * @author embeddedt
+     * @reason Reuse the existing blockstate list held by Forge instead of making a new one
+     */
+    @Redirect(method = "initValidStates", at = @At(value = "INVOKE", target = "Ljava/util/stream/Stream;collect(Ljava/util/stream/Collector;)Ljava/lang/Object;", ordinal = 0), remap = false)
+    private static Object getStateList(Stream<?> instance, Collector<?, ?, ?> arCollector) {
+        var idMapper = GameData.getBlockStateIDMap();
+        return new AbstractList<>() {
+            @Override
+            public int size() {
+                return idMapper.size();
+            }
+
+            @Override
+            public Object get(int index) {
+                var o = idMapper.byId(index);
+                if (o == null) {
+                    throw new IndexOutOfBoundsException();
+                }
+                return o;
+            }
+        };
+    }
+}