org.eclipse.jetty.websocket.servlet.WebSocketServlet cleanup

[VasilVasilev93]

Jetty version
9.4.30.v20200611

Description
Hello and happy new year, wish you all the best!
Ater using websocket-servlet in osgi environment, I found that a single instance of org.eclipse.jetty.websocket.servlet.WebSocketServletFactory always remains in memory after uninstall of the bundle jar. Looking at the code it seems that the factory object is not getting removed from the context's attributes map. Inside the init method:
ctx.setAttribute(WebSocketServletFactory.class.getName(), factory);

In the destroy method only factory.stop(); gets called. If we also remove it from the context's attributes map, the object gets cleaned up. We have that fixed in our product, but I wonder if it's intended or a miss.

[lachlan-roberts]

I think the ServletContext attributes should be cleared when the context is stopped, so if you're getting to destroy then the attributes should be cleared shortly after. @janbartel any idea why this would be happening?

Your suggested cleanup sounds reasonable so I will put a PR up for this, thanks.

[lachlan-roberts]

We now remove the WebSocketServletFactory ServletContext attribute in the destroy method.