src/game/java/net/minecraft/data/worldgen/AncientCityStructurePieces.java

package net.minecraft.data.worldgen;

import com.google.common.collect.ImmutableList;
import com.mojang.datafixers.util.Pair;
import net.minecraft.core.Holder;
import net.minecraft.core.HolderGetter;
import net.minecraft.core.registries.Registries;
import net.minecraft.resources.ResourceKey;
import net.minecraft.world.level.levelgen.structure.pools.StructurePoolElement;
import net.minecraft.world.level.levelgen.structure.pools.StructureTemplatePool;
import net.minecraft.world.level.levelgen.structure.templatesystem.StructureProcessorList;

public class AncientCityStructurePieces {
    public static final ResourceKey<StructureTemplatePool> START = Pools.createKey("ancient_city/city_center");

    public static void bootstrap(BootstrapContext<StructureTemplatePool> p_331025_) {
        HolderGetter<StructureProcessorList> holdergetter = p_331025_.lookup(Registries.PROCESSOR_LIST);
        Holder<StructureProcessorList> holder = holdergetter.getOrThrow(ProcessorLists.ANCIENT_CITY_START_DEGRADATION);
        HolderGetter<StructureTemplatePool> holdergetter1 = p_331025_.lookup(Registries.TEMPLATE_POOL);
        Holder<StructureTemplatePool> holder1 = holdergetter1.getOrThrow(Pools.EMPTY);
        p_331025_.register(
            START,
            new StructureTemplatePool(
                holder1,
                ImmutableList.of(
                    Pair.of(StructurePoolElement.single("ancient_city/city_center/city_center_1", holder), 1),
                    Pair.of(StructurePoolElement.single("ancient_city/city_center/city_center_2", holder), 1),
                    Pair.of(StructurePoolElement.single("ancient_city/city_center/city_center_3", holder), 1)
                ),
                StructureTemplatePool.Projection.RIGID
            )
        );
        AncientCityStructurePools.bootstrap(p_331025_);
    }
}