Command Class

package net.mccity.adrew1.mccitychat.commands;

import com.google.common.io.ByteArrayDataOutput;
import com.google.common.io.ByteStreams;
import net.kyori.adventure.text.minimessage.MiniMessage;
import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
import net.mccity.adrew1.mccitychat.McCityChat;
import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.jetbrains.annotations.NotNull;

public class GCommand implements CommandExecutor {
    @Override
    public boolean onCommand(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {

        if (!(sender instanceof Player)) {
            sender.sendMessage("Must be a player");
            return true;
        }

        Player player = (Player) sender;

        ByteArrayDataOutput out = ByteStreams.newDataOutput();
        out.writeUTF("MessageRaw");
        out.writeUTF("ALL");

        StringBuilder builder = new StringBuilder();
        for (String string : args) {
            builder.append(string).append(" ");
        }

        String message = builder.toString().trim();

        out.writeUTF(GsonComponentSerializer.gson().serialize(MiniMessage.miniMessage().deserialize(message)));
        sender.sendMessage("Sending msg");

       player.sendPluginMessage(McCityChat.plugin, "mccity:chat", out.toByteArray());

        return true;
    }
}