code: protected Collection<CommunicationSummaryStatistics> doGetCommunicationSummaryStatistics(String tenantId, Criteria criteria) {
          String index = client.getIndex(tenantId);
          Map<String, CommunicationSummaryStatistics> stats = new HashMap<>();
  
          if (!criteria.transactionWide()) {
              Criteria txnWideCriteria = criteria.deriveTransactionWide();
              buildCommunicationSummaryStatistics(stats, index, txnWideCriteria, false);
          }
  
          buildCommunicationSummaryStatistics(stats, index, criteria, true);
          return stats.values();
      }
docs: This method returns the flat list of communication summary stats.
  
  @param tenantId The tenant id
  @param criteria The criteria
  @return The list of communication summary nodes