Example Code

import java.util.Collection;
import java.util.UUID;
import java.util.concurrent.TimeoutException;
import java.util.logging.Level;
 
import org.bukkit.plugin.java.JavaPlugin;
 
import net.md_5.bungee.BungeeCord;
import net.md_5.bungee.api.config.ServerInfo;
import net.md_5.bungee.api.plugin.Plugin;
import septogeddon.pluginquery.PluginQuery;
import septogeddon.pluginquery.api.QueryConnection;
import septogeddon.pluginquery.api.QueryConnectionStateListener;
import septogeddon.pluginquery.api.QueryContext;
import septogeddon.pluginquery.api.QueryListener;
import septogeddon.pluginquery.api.QueryMessageListener;
import septogeddon.pluginquery.api.QueryMessenger;
import septogeddon.pluginquery.bungeecord.BungeePluginQuery;
import septogeddon.pluginquery.library.remote.ClassRegistry;
import septogeddon.pluginquery.library.remote.RemoteObject;
import septogeddon.pluginquery.library.remote.Represent;
import septogeddon.pluginquery.library.remote.UnknownObject;
 
@SuppressWarnings("all")
public class Example {
 
    /*
     * Send plugin message to all active connections.
     * (Spigot to BungeeCord / BungeeCord to Spigot)
     */
    public void sendPluginMessage(String channel, byte[] message) {
        QueryMessenger messenger = PluginQuery.getMessenger();
        /*
         * A spigot server can be connected with multiple connection,
         * it can be a bungeecord server or another standalone program
         */
        if (!messenger.broadcastQuery(channel, message)) {
            // it will return false if there is no active connections
            throw new IllegalStateException("no active connections");
        }
    }
     
    /*
     * Send plugin message to a server
     * (BungeeCord to Server)
     */
    public void sendPluginMessage(ServerInfo info, String channel, byte[] message) {
        /*
         * If this returns null, then the Spigot server is not connected to the BungeeCord
         * Invalid key perhaps?
         */
        QueryConnection connection = BungeePluginQuery.getConnection(info);
        if (connection != null) {
            connection.sendQuery(channel, message);
        } else {
            throw new IllegalArgumentException("server is not yet connected");
        }
    }
     
    /*
     * Register listeners to listen to Query Events
     */
    public void registerListener() {
        QueryMessenger messenger = PluginQuery.getMessenger();
        messenger.getEventBus().registerListener(new ExampleListener());
        messenger.getEventBus().registerListener(new ExampleListener2());
        messenger.getEventBus().registerListener(new ExampleListener3());
         
        net.md_5.bungee.api.plugin.Plugin plugin = null; // YOUR BUNGEECORD PLUGIN INSTANCE
        BungeeCord.getInstance().getPluginManager().registerListener(plugin, new ExampleListener4());
    }
     
    /*
     * Listen only to Message event
     */
    public class ExampleListener implements QueryMessageListener {
 
        @Override
        public void onQueryReceived(QueryConnection connection, String channel, byte[] message) {
            // QUERY RECEIVED
        }
         
    }
     
    /*
     * Listen only to Connection State event
     */
    public class ExampleListener2 implements QueryConnectionStateListener {
 
        @Override
        public void onConnectionStateChange(QueryConnection connection) {
            if (connection.isConnected()) {
                // CONNECTED!
            } else {
                // DISCONNECTED!
            }
        }
         
    }
     
    /*
     * Listen to Message and Connection State event
     */
    public class ExampleListener3 implements QueryListener {
 
        @Override
        public void onConnectionStateChange(QueryConnection connection) {
            if (connection.isConnected()) {
                // CONNECTED!
            } else {
                // DISCONNECTED!
            }
        }
 
        @Override
        public void onQueryReceived(QueryConnection connection, String channel, byte[] message) {
            // QUERY RECEIVED
        }
         
    }
     
    /*
     * Listen Query Message using BungeeCord event API
     */
    public class ExampleListener4 implements net.md_5.bungee.api.plugin.Listener {
         
        @net.md_5.bungee.event.EventHandler
        public void event(septogeddon.pluginquery.bungeecord.event.QueryMessageEvent event) {
            // the channel
            String channel = event.getTag();
            // the message
            byte[] message = event.getMessage();
            // the connection
            QueryConnection connection = event.getSender();
            // same thing
            connection = event.getReceiver();
        }
         
    }
     
    public class ExampleListener5 implements org.bukkit.event.Listener {
         
        @org.bukkit.event.EventHandler
        public void event(septogeddon.pluginquery.spigot.event.QueryMessageEvent event) {
            // the channel
            String channel = event.getChannel();
            // the message
            byte[] message = event.getMessage();
            // the connection
            QueryConnection connection = event.getConnection();
        }
         
    }
     
}
 
class RemoteObjectExample {
     
    public void spigotSide(JavaPlugin plugin) {
        // get the only one active bungeecord connection
        QueryConnection connection = QueryUtil.first(PluginQuery.getMessenger().getActiveConnections());
        // create the remote
        RemoteObject<SimpleProxyServer> remoteObject = new RemoteObject<SimpleProxyServer>(
                /* Parameter */
                QueryContext.REMOTEOBJECT_BUNGEESERVER_CHANNEL, 
                connection, 
                SimpleProxyServer.class, 
                new ClassRegistry()
                );
         
        // get the object from the bungeecord
        try {
            SimpleProxyServer server = remoteObject.getObject();
            // use UnknownObject interface, so you don't have to create another empty interface
            UnknownObject lobby = server.getServerInfo("lobby");
            for (SimpleProxiedPlayer player : server.getPlayers()) {
                player.connect(lobby);
                plugin.getLogger().log(Level.INFO, "Transfered "+player.getName()+" ("+player.getUniqueId()+") to lobby server");
            }
        } catch (TimeoutException e) {
            // The connection took too long :(
            // perhaps network problem?
            e.printStackTrace();
        }
    }
     
    public void bungeecordSide(Plugin plugin) {
        ClassRegistry registry = new ClassRegistry();
        for (QueryConnection connection : PluginQuery.getMessenger().getActiveConnections()) {
            RemoteObject<SimpleServer> remoteObject= new RemoteObject<>(
                    QueryContext.REMOTEOBJECT_BUKKITSERVER_CHANNEL,
                    connection,
                    SimpleServer.class,
                    registry
                    );
            try {
                SimpleServer server = remoteObject.getObject();
                for (SimplePlayer player : server.getOnlinePlayers()) {
                    player.kickPlayer("Kicked, bye!");
                }
            } catch (TimeoutException e) {
                // The connection took too long :(
                // perhaps network problem?
                e.printStackTrace();
            }
        }
    }
     
    @Represent("org.bukkit.Server")
    public static interface SimpleServer {
        public String getVersion();
        public Collection<? extends SimplePlayer> getOnlinePlayers();
    }
     
    @Represent("org.bukkit.entity.Player")
    public static interface SimplePlayer {
        public void kickPlayer(String kickMessage);
    }
     
    @Represent("net.md_5.bungee.api.ProxyServer")
    public static interface SimpleProxyServer {
        public String getVersion();
        public SimpleProxiedPlayer getPlayer(String playerName);
        public SimpleProxiedPlayer getPlayer(UUID playerUUID);
        public Collection<SimpleProxiedPlayer> getPlayers();
        public UnknownObject getServerInfo(String name);
    }
     
    @Represent("net.md_5.bungee.api.connection.ProxiedPlayer")
    public static interface SimpleProxiedPlayer {
        public String getName();
        public int getPing();
        public UUID getUniqueId();
        public String getDisplayName();
        public void disconnect(String kickMessage);
        public void connect(UnknownObject server);
    }
     
}

Source: https://github.com/septogeddon/PluginQuery/blob/master/PluginQuery/src/septogeddon/pluginquery/utils/Example.java