code: final void addHandler(final HttpHandler handler) {
      if (handler != null) {
        if (!eventHandlers.containsKey(handler.getUriSpecification().toLowerCase())) {
          eventHandlers.put(handler.getUriSpecification().toLowerCase(), handler);
        } else {
          LOG.log(Level.WARNING, "JettyHandler handle is already registered: {0} ", handler.getUriSpecification());
        }
      }
    }
docs: Add a handler explicitly instead of through injection. This is for handlers created on the fly.
  
  @param handler