It looks like spawn list entry is no longer on mappings channel: 'snapshot', version: '20210309-1.16.5' so i wrote this down instead:
package com.fmom.cb.world.gen;
import com.fmom.cb.Main;
import com.fmom.cb.init.ModEntityTypes;
import net.minecraft.entity.EntityClassification;
import net.minecraft.world.biome.MobSpawnInfo;
import net.minecraftforge.event.world.BiomeLoadingEvent;
import net.minecraftforge.eventbus.api.SubscribeEvent;
import net.minecraftforge.fml.common.Mod;
@Mod.EventBusSubscriber(modid = Main.MODID, bus = Mod.EventBusSubscriber.Bus.FORGE)
public class ModEntitySpawns {
@SubscribeEvent
public static void onBiomeLoading(BiomeLoadingEvent e) {
e.getSpawns().withSpawner(EntityClassification.CREATURE, new MobSpawnInfo.Spawners(ModEntityTypes.CAPYBARA.get(), 100, 5, 5));
}
}