http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
public interface io.netty.handler.codec.http.websocketx.extensions.WebSocketServerExtension extends io.netty.handler.codec.http.websocketx.extensions.WebSocketExtension
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: io.netty.handler.codec.http.websocketx.extensions.WebSocketServerExtension
  super_class: java.lang.Object
{
  public abstract io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionData newReponseData();
    descriptor: ()Lio/netty/handler/codec/http/websocketx/extensions/WebSocketExtensionData;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
SourceFile: "WebSocketServerExtension.java"