Using Javalin in a Spigot or Bungeecord Plugin
A common problem when attempting to use Javalin in a Spigot or Bungeecord plugin is the following:
[ERROR] java.lang.RuntimeException: javax.servlet.ServletException: java.lang.RuntimeException: Unable to load org.eclipse.jetty.websocket.server.WebSocketServerFactory ... Caused by: java.lang.ClassNotFoundException: org.eclipse.jetty.websocket.server.WebSocketServerFactory
This is incredibly frustrating because as far as you can tell, you've included all of Javalin's dependencies properly. In fact, you're probably reading this guide right now because you yourself fell victim to these pesky errors. Don't get too fraught, the solution is right under your nose!