private static <R, S, P extends Message, Q extends Message, T extends Message> S
    getPromotedValueFromProto(ColumnInterpreter<R, S, P, Q, T> ci, AggregateResponse resp,
      int firstPartIndex) throws IOException {
    T t = getParsedGenericInstance(ci.getClass(), 4, resp.getFirstPart(firstPartIndex));
    return ci.getPromotedValueFromProto(t);
  }
This client class is for invoking the aggregate functions deployed on the Region Server side via
the AggregateService. This class will implement the supporting functionality for
summing/processing the individual results obtained from the AggregateService for each region.
hbase-endpoint/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AsyncAggregationClient.java