public static GenericServlet unregisterServlet(Plugin plugin, String url)
            throws ServletException {
        String pluginName = pluginManager.getPluginPath(plugin).getFileName().toString();
        if (url == null) {
            throw new ServletException("Servlet URL is missing");
        }
        String fullUrl = pluginName + url;
        return servlets.remove(fullUrl.toLowerCase());
    }
Unregister a live servlet for a plugin programmatically. Does not call
the servlet destroy method.

@param plugin the owner of the servlet
@param url the relative url where servlet has been bound
@return the unregistered servlet, so that it can be destroyed
@throws ServletException if the URL is missing
xmppserver/src/main/java/org/jivesoftware/openfire/container/PluginServlet.java