package net.glowstone.net.message.login;

import com.flowpowered.networking.Message;
import lombok.Data;

@Data
public final class LoginStartMessage implements Message {

    private final String username;

}

package net.glowstone.net.message.login;

import com.flowpowered.networking.AsyncableMessage;
import lombok.Data;

@Data
public final class LoginStartMessage implements AsyncableMessage {

    private final String username;

}

Make LoginStartMessage async