SPIGOT-7211: generateTree() with Consumer or Predicate is broken

By: md_5 <git@md-5.net>

paper-server/src/main/java/org/bukkit/craftbukkit/util/BlockStateListPopulator.java

@@ -8,6 +8,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.Predicate;
 import net.minecraft.core.BlockPosition;
+import net.minecraft.core.IRegistryCustom;
 import net.minecraft.server.level.WorldServer;
 import net.minecraft.world.level.GeneratorAccess;
 import net.minecraft.world.level.block.ITileEntity;
@@ -126,8 +127,18 @@ public class BlockStateListPopulator extends DummyGeneratorAccess {
         return predicate.test(getBlockState(blockposition));
     }
 
+    @Override
+    public boolean isFluidAtPosition(BlockPosition bp, Predicate<Fluid> prdct) {
+        return world.isFluidAtPosition(bp, prdct);
+    }
+
     @Override
     public DimensionManager dimensionType() {
         return world.dimensionType();
     }
+
+    @Override
+    public IRegistryCustom registryAccess() {
+        return world.registryAccess();
+    }
 }