Set context class loader in server thread

Author: Trollhunters501

src/main/java/org/barrelmc/barrel/NukkitMain.java

@@ -33,6 +33,7 @@ public void onEnable(){
       saveResource("config.yml");
     }
     this.threadJavaServer = new Thread(()->{
+      Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());
       BlockConverter.init();
       ItemsConverter.init();
       this.javaServer = new ProxyServer(data_pathJava);