code: public boolean addExtraDataParser(BeaconParser extraDataParser) {
          //add an extra data parser only if it is not null and it is an extra frame parser
          return extraDataParser != null && extraDataParser.mExtraFrame && extraParsers.add(extraDataParser);
      }
docs: Adds a <code>BeaconParser</code> used for parsing extra BLE beacon advertisement packets for
  beacons that send multiple different advertisement packets (for example, Eddystone-TLM)
  
  @param extraDataParser a parser that must be configured with an "extra layout" prefix
  @return true when the extra parser is added successfully