Full example of a plugin that uses the custom event of HealthBar

package test.use.healthbar;

import org.bukkit.OfflinePlayer;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;

import com.gmail.davideblade99.healthbar.api.BarHideEvent; // Event import

public class Main extends JavaPlugin implements Listener {

@Override
public void onEnable() {

    // Check if the plugin is loaded
    if (getServer().getPluginManager().getPlugin("HealthBar-Reloaded") != null)
        getServer().getPluginManager().registerEvents(this, this);
}

@Override
public void onDisable() {}

@EventHandler
public void onBarHide(BarHideEvent event) {
    // You don't need the online player for scoreboards
    OfflinePlayer player = event.getOfflinePlayer();

    // Prints the name of the player whose tag has been restored
    System.out.println(player.getName());

    // More stuff
    // ...
    // Add the player to a team for example
}

}