How to cancel reeling in a fish.

CancelReelingIn.java

package com.comphenix.example;

import java.util.Collections;
import java.util.Set;

import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerFishEvent;
import org.bukkit.event.player.PlayerFishEvent.State;
import org.bukkit.plugin.java.JavaPlugin;

import com.comphenix.protocol.PacketType;
import com.comphenix.protocol.ProtocolLibrary;
import com.comphenix.protocol.events.PacketAdapter;
import com.comphenix.protocol.events.PacketEvent;
import com.google.common.collect.MapMaker;

public class CancelReelingIn extends JavaPlugin implements Listener {
    private Set<Player> fishers = Collections.newSetFromMap(new MapMaker().weakKeys().<Player, Boolean>makeMap());
    
    @Override
    public void onEnable() {
        ProtocolLibrary.getProtocolManager().addPacketListener(
          new PacketAdapter(this, PacketType.Play.Client.BLOCK_PLACE) { 
            @Override
            public void onPacketReceiving(PacketEvent event) {
                if (fishers.contains(event.getPlayer())) {
                    event.setCancelled(true);
                    System.out.println("Cancelling packet.");
                }
            }
        });
        
        getServer().getPluginManager().registerEvents(this, this);
    }
    
    @EventHandler
    public void onPlayerFishEvent(PlayerFishEvent e) {
        if (e.getState() == State.FISHING) {
            fishers.add(e.getPlayer());
        } else {
            fishers.remove(e.getPlayer());
        }
    }
}