Compiles again.

src/main/java/appeng/mixins/ThreadedAnvilChunkStorageAccessor.java

@@ -0,0 +1,14 @@
+package appeng.mixins;
+
+import net.minecraft.world.chunk.listener.IChunkStatusListener;
+import net.minecraft.world.server.ChunkManager;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+@Mixin(ChunkManager.class)
+public interface ThreadedAnvilChunkStorageAccessor {
+
+    @Accessor("field_219266_t")
+    IChunkStatusListener getWorldGenerationProgressListener();
+
+}