Code review comment: Please populate as done in the other PRs

Code under review:
public boolean start() throws IOException {
      RowSet.Builder rowSetBuilder = RowSet.newBuilder();
      for (ByteKeyRange sourceRange : source.getRanges()) {
        rowSetBuilder =
            rowSetBuilder.addRowRanges(
                RowRange.newBuilder()
                    .setStartKeyClosed(ByteString.copyFrom(sourceRange.getStartKey().getValue()))
                    .setEndKeyOpen(ByteString.copyFrom(sourceRange.getEndKey().getValue())));
      }
      RowSet rowSet = rowSetBuilder.build();

      String tableNameSr =
          session.getOptions().getInstanceName().toTableNameStr(source.getTableId().get());

      HashMap<String, String> baseLabels = new HashMap<>();
      baseLabels.put(MonitoringInfoConstants.Labels.PTRANSFORM, "");
      baseLabels.put(MonitoringInfoConstants.Labels.SERVICE, "BigTable");
      baseLabels.put(MonitoringInfoConstants.Labels.METHOD, "google.bigtable.v2.ReadRows");
      baseLabels.put(MonitoringInfoConstants.Labels.RESOURCE, "");
      baseLabels.put(
          MonitoringInfoConstants.Labels.BIGTABLE_PROJECT_ID, session.getOptions().getProjectId());
      baseLabels.put(
          MonitoringInfoConstants.Labels.INSTANCE_ID, session.getOptions().getInstanceId());
      baseLabels.put(
          MonitoringInfoConstants.Labels.TABLE_ID,
          GcpResourceIdentifiers.bigtableTableID(
              session.getOptions().getProjectId(),
              session.getOptions().getInstanceId(),
              source.getTableId().get()));
      ServiceCallMetric serviceCallMetric =
          new ServiceCallMetric(MonitoringInfoConstants.Urns.API_REQUEST_COUNT, baseLabels);
      ReadRowsRequest.Builder requestB =
          ReadRowsRequest.newBuilder().setRows(rowSet).setTableName(tableNameSr);
      if (source.getRowFilter() != null) {
        requestB.setFilter(source.getRowFilter());
      }
      results = session.getDataClient().readRows(requestB.build());
      serviceCallMetric.call("ok");
      return advance();
    }

Line commented on: baseLabels.put(MonitoringInfoConstants.Labels.RESOURCE, "");

Revised code:
public boolean start() throws IOException {
      RowSet.Builder rowSetBuilder = RowSet.newBuilder();
      for (ByteKeyRange sourceRange : source.getRanges()) {
        rowSetBuilder =
            rowSetBuilder.addRowRanges(
                RowRange.newBuilder()
                    .setStartKeyClosed(ByteString.copyFrom(sourceRange.getStartKey().getValue()))
                    .setEndKeyOpen(ByteString.copyFrom(sourceRange.getEndKey().getValue())));
      }
      RowSet rowSet = rowSetBuilder.build();

      String tableNameSr =
          session.getOptions().getInstanceName().toTableNameStr(source.getTableId().get());

      HashMap<String, String> baseLabels = new HashMap<>();
      baseLabels.put(MonitoringInfoConstants.Labels.PTRANSFORM, "");
      baseLabels.put(MonitoringInfoConstants.Labels.SERVICE, "BigTable");
      baseLabels.put(MonitoringInfoConstants.Labels.METHOD, "google.bigtable.v2.ReadRows");
      baseLabels.put(
          MonitoringInfoConstants.Labels.RESOURCE,
          GcpResourceIdentifiers.bigtableResource(
              session.getOptions().getProjectId(),
              session.getOptions().getInstanceId(),
              source.getTableId().get()));
      baseLabels.put(
          MonitoringInfoConstants.Labels.BIGTABLE_PROJECT_ID, session.getOptions().getProjectId());
      baseLabels.put(
          MonitoringInfoConstants.Labels.INSTANCE_ID, session.getOptions().getInstanceId());
      baseLabels.put(
          MonitoringInfoConstants.Labels.TABLE_ID,
          GcpResourceIdentifiers.bigtableTableID(
              session.getOptions().getProjectId(),
              session.getOptions().getInstanceId(),
              source.getTableId().get()));
      ServiceCallMetric serviceCallMetric =
          new ServiceCallMetric(MonitoringInfoConstants.Urns.API_REQUEST_COUNT, baseLabels);
      ReadRowsRequest.Builder requestB =
          ReadRowsRequest.newBuilder().setRows(rowSet).setTableName(tableNameSr);
      if (source.getRowFilter() != null) {
        requestB.setFilter(source.getRowFilter());
      }
      try {
        results = session.getDataClient().readRows(requestB.build());
        serviceCallMetric.call("ok");
      } catch (StatusRuntimeException e) {
        serviceCallMetric.call(e.getStatus().getCode().value());
        throw e;
      }
      return advance();
    }