code: @POST
      @Broadcast(filters = {StringFilterAggregator.class})
      @Path("aggregate")
      public Broadcastable aggregate(@FormParam("message") String message) {
          return broadcast(message);
      }
docs: Retain Broadcast events until we have enough data. See the {@link StringFilterAggregator}
  to configure the amount of data buffered before the events gets written
  back to the set of suspended response.
  
  @param message A String from an HTML form
  @return A {@link Broadcastable} used to broadcast events.