code: protected boolean shouldRenderId(
        FacesContext context,
        UIComponent  component)
      {
        String id = component.getId();
  
        // Otherwise, if ID isn't set, don't bother
        if (id == null)
        {
            return false;
        }
  
        // ... or if the ID was generated, don't bother
        if (id.startsWith(UIViewRoot.UNIQUE_ID_PREFIX))
        {
            return false;
        }
  
        return true;
      }
docs: Returns true if the component should render an ID.  Components
  that deliver events should always return "true".
  @todo Is this a bottleneck?  If so, optimize!