code: public Iterator<BaseMessageFilter> getFilterList(BaseMessageHeader messageHeader)
      {
          if (messageHeader == null)
              return super.getFilterList(messageHeader);  // ALL The filters
          return this.getRegistry().getFilterList(messageHeader);
      }
docs: Get the list of filters for this message header.
  Override this to implement another (tree?) filter.
  @param messageHeader The message header to get the list for (if null, return ALL the filters).
  @return The list of filters.