Forma simples de resetar lentamente uma área de blocos.

Mine.java

package com.drazyh.mines;

import com.drazyh.common.spigot.SpigotConstants;
import com.drazyh.common.spigot.location.SerializedLocation;
import com.drazyh.common.spigot.misc.utils.ProbabilityCollection;
import com.drazyh.common.spigot.misc.utils.WorldCuboid;
import com.drazyh.mines.api.MineOre;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.RequiredArgsConstructor;
import lombok.Setter;
import org.bukkit.Bukkit;
import org.bukkit.Location;
import org.bukkit.block.Block;
import org.bukkit.entity.Entity;
import org.bukkit.entity.EntityType;
import org.bukkit.event.player.PlayerTeleportEvent;
import org.bukkit.scheduler.BukkitRunnable;

import java.util.ArrayDeque;
import java.util.List;
import java.util.Queue;
import java.util.stream.Collectors;

@RequiredArgsConstructor
@Getter
@EqualsAndHashCode(of = "id")
public class Mine {

    private final int id;

    private final String displayName;

    @Setter
    private SerializedLocation joinLocation;

    @Setter
    private WorldCuboid cuboid;

    @Setter
    private long delayInMills;

    private Long lastReseted;

    @Setter
    private ProbabilityCollection<MineOre> ores;

    public boolean canReset() {

        if (lastReseted == null) {
            return true;
        }

        long diff = System.currentTimeMillis() - lastReseted;

        return diff >= delayInMills;
    }

    public void reset() {
        if (cuboid == null) {
            System.out.println("Cuboid nulo. ID: " + this.id);

            MineConstants.CURRENT_RESETING_MINE_ID.set(0);

            return;
        }

        if (this.ores.isEmpty()) {

            System.out.println("Sem ores. ID: " + this.id);

            MineConstants.CURRENT_RESETING_MINE_ID.set(0);

            return;
        }

        List<Entity> entities = Bukkit.getWorld(cuboid.getWorldName()).getEntities().stream()
                .filter(entity -> entity.getType() == EntityType.PLAYER)
                .filter(entity -> cuboid.contains(entity.getLocation(), true))
                .collect(Collectors.toList());

        if (!entities.isEmpty()) {
            Bukkit.getScheduler().runTask(MinesPlugin.INSTANCE, () -> teleportEntities(entities));
        }

        int blocks0 = cuboid.getBlocks0();

        final Queue<Block> blocks = new ArrayDeque<>(blocks0);

        computeBlocks(blocks);

        processBlocks(blocks, () -> {
            System.out.println("Finalizei de resetar mina '" + getDisplayName() + "'.");

            lastReseted = System.currentTimeMillis();

            MineConstants.CURRENT_RESETING_MINE_ID.set(0);

            blocks.clear();
        });
    }

    private void computeBlocks(Queue<Block> blocks) {
        boolean onlyAir = lastReseted != null;

        if (onlyAir) {
            System.out.println("Resetando onlyAir na mina " + getId());
        }

        cuboid.getTopToBottomBlocks(blocks::add, onlyAir);
    }

    private void processBlocks(Queue<Block> blocks, Runnable notifyRunnable) {

        new BukkitRunnable() {
            @Override
            public void run() {
                for (int i = 0; i < 180; i++) {
                    Block poll = blocks.poll();

                    if (poll == null) {
                        this.cancel();

                        notifyRunnable.run();
                        break;
                    }

                    poll.setType(ores.get().getMaterial());
                }
            }
        }.runTaskTimer(MinesPlugin.INSTANCE, 1L, 10L);

    }

    private void teleportEntities(List<Entity> entities) {
        Location parser = getJoinLocation().parser(SpigotConstants.LOCATION_PARSER);

        for (Entity entity : entities) {
            if (entity.getType() != EntityType.PLAYER) {
                continue;
            }

            entity.teleport(parser, PlayerTeleportEvent.TeleportCause.UNKNOWN);
        }
    }

}