@Override
 public void onGroupLoaded(TickerGroup tickerGroup) {
   ConversionTable.Builder builder = ConversionTable.newBuilder();
   for (Ticker ticker : tickerGroup) {
     builder.incorporate(ticker);
   }
   ConversionTable conversionTable = builder.build();
   value.add(tickerGroup, conversionTable);
   groupCallback.onGroupLoaded(tickerGroup, conversionTable);
 }
 public void replay(OnGroupLoad groupCallback) {
   for (int i = 0; i < tickerGroups.size(); i++) {
     groupCallback.onGroupLoaded(tickerGroups.get(i), conversionTables.get(i));
   }
 }