@EventHandler
public void onJoin(final PlayerJoinEvent e) {
    TextComponent message = new TextComponent( "Click me" );
    message.setClickEvent( new ClickEvent( ClickEvent.Action.OPEN_URL, "https://www.spigotmc.org" ) );
    message.setHoverEvent( new HoverEvent( HoverEvent.Action.SHOW_TEXT, new ComponentBuilder( "Visit the Spigot website!" ).create() ) );
    e.getPlayer().spigot().sendMessage(message);
}