Bukkit / Spigot message sender with placeholder and prefix ability

Messages.java

import com.earth2me.essentials.Essentials;
import com.earth2me.essentials.User;
import com.google.common.collect.Maps;
import de.leonhard.storage.Toml;
import org.apache.commons.lang.text.StrSubstitutor;
import org.bukkit.ChatColor;
import org.bukkit.OfflinePlayer;
import org.bukkit.command.CommandSender;

import java.util.Map;
import java.util.UUID;

public class Messages {

    private static final Toml config = new Toml("messages",UnitedAnimals.getMain().getDataFolder().toString(),
            UnitedAnimals.class.getClassLoader().getResourceAsStream("messages.toml"));
    private final Map<String, Object> placeholders = Maps.newHashMap();
    private final String path;

    public static Messages of(String path) {
        return new Messages(path);
    }

    private Messages(String path) {
        this.path = path;
        placeholders.put("prefix", config.get("prefix", ""));
    }

    public String build() {
        String message = config.get(path, path);
        message = replace(message);
        return ChatColor.translateAlternateColorCodes('&', message);
    }

    public Messages vars(Map<String, Object> placeholders) {
        this.placeholders.putAll(placeholders);
        return this;
    }

    public Messages var(String name, Object value) {
        placeholders.put(name, value);
        return this;
    }

    public void send(CommandSender sender) {
        if (sender != null)
            sender.sendMessage(build());
    }

    public void sendOffline(OfflinePlayer player) {
        if (player.isOnline())
            send(player.getPlayer());
    }

    public void asMail(OfflinePlayer player) {
        asMail(player.getUniqueId());
    }

    public void asMail(UUID uuid) {
        Essentials essentials = UnitedAnimals.getMain().getEssentials();
        if (essentials == null)
            return;

        User user = essentials.getUser(uuid);
        if (user == null)
            return;

        String builded = build();
        if (user.getMails().contains(builded))
            return;

        user.addMail(builded);
        user.notifyOfMail();
    }

    private String replace(String string) {
        return StrSubstitutor.replace(string, placeholders, "%", "%");
    }
}