LootPool.java

import java.util.List;

public class LootPool {
    private int rolls;
    private List<String> entries;

    public LootPool(int rolls, List<String> entries) {
        this.rolls = rolls;
        this.entries = entries;
    }
}

LootTable.java

import java.util.Arrays;
import java.util.List;

public class LootTable {
    private String type;
    private List<LootPool> pools;

    public LootTable(String type, List<LootPool> pools) {
        this.type = type;
        this.pools = pools;
    }

    public static final void main(String[] args) {
        List<String> lootDrops = Arrays.asList("minecraft:diamond", "aycessentials:saturn");
        LootPool pool1 = new LootPool(1, lootDrops);
        List<String> lootDrops2 = Arrays.asList("minecraft:gold", "minecraft:diamond");
        LootPool pool2 = new LootPool(2, lootDrops2);

        List<LootPool> lootPools = Arrays.asList(pool1, pool2);
        LootTable lootTable = new LootTable("minecraft:block", lootPools);
    }
}