This is a wrapper for Listener classes that I use for Spigot's Listener API.

PluginDependent.java

package jab.util.spigot;

import org.bukkit.plugin.java.JavaPlugin;

import jab.util.Printable;

/**
 * This class is designed to clean up redundant JavaPlugin getters and setters.
 *
 * @author Jab
 */
public abstract class PluginDependent<P extends JavaPlugin> implements Printable {

  /** The JavaPlugin dependency. */
  private P plugin;

  /**
   * Requires a JavaPlugin.
   *
   * @param plugin
   */
  public PluginDependent(P plugin) {
    setPlugin(plugin);
  }

  /**
   * Returns the JavaPlugin dependency.
   *
   * @return
   */
  public P getPlugin() {
    return this.plugin;
  }

  /**
   * Sets the JavaPlugin dependency.
   *
   * @param plugin
   */
  private void setPlugin(P plugin) {
    this.plugin = plugin;
  }
}

PluginDependentListener.java

package jab.util.spigot;

import org.bukkit.Bukkit;
import org.bukkit.event.HandlerList;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;
import org.jetbrains.annotations.NotNull;

/**
 * This utility class handles common operations of plugin-dependent event-listeners for the Spigot
 * Listener API.
 *
 * @author Jab
 * @param <P> The JavaPlugin each implementation depends on.
 */
public abstract class PluginDependentListener<P extends JavaPlugin> extends PluginDependent<P>
    implements Listener {

  private boolean registered;

  /**
   * Main constructor.
   *
   * @param plugin The dependent plug-in.
   */
  public PluginDependentListener(@NotNull P plugin) {
    super(plugin);
  }

  /** Registers the events listened to by this Listener. */
  public void register() {
    if (!registered) {
      Bukkit.getServer().getPluginManager().registerEvents(this, getPlugin());
      registered = true;
    }
  }

  /** Unregisters the Listener. */
  public void unregister() {
    if (registered) {
      HandlerList.unregisterAll(this);
      registered = false;
    }
  }

  @Override
  public String getName() {
    return getClassName();
  }
}