code: @Override
      public String getActionURL(FacesContext facesContext, String viewId) {
          facesContext.getAttributes().put(Container.CONTEXT_ID_KEY, contextID);
          return super.getActionURL(facesContext, viewId);
      }
docs: Allow the delegate to produce the action URL. If the conversation is
  long-running, append the conversation id request parameter to the query
  string part of the URL, but only if the request parameter is not already
  present.
  <p/>
  This covers form actions Ajax calls, and redirect URLs (which we want)
  and link hrefs (which we don't)
  
  @see {@link ViewHandler#getActionURL(FacesContext, String)}