code: @Override
      public ResponseEntity<MgmtSystemStatisticsRest> getSystemUsageStats() {
          final SystemUsageReportWithTenants report = systemManagement.getSystemUsageStatisticsWithTenants();
  
          final MgmtSystemStatisticsRest result = new MgmtSystemStatisticsRest()
                  .setOverallActions(report.getOverallActions()).setOverallArtifacts(report.getOverallArtifacts())
                  .setOverallArtifactVolumeInBytes(report.getOverallArtifactVolumeInBytes())
                  .setOverallTargets(report.getOverallTargets()).setOverallTenants(report.getTenants().size());
  
          result.setTenantStats(report.getTenants().stream().map(MgmtSystemManagementResource::convertTenant)
                  .collect(Collectors.toList()));
  
          return ResponseEntity.ok(result);
      }
docs: Collects and returns system usage statistics. It provides a system wide
  overview and tenant based stats.
  
  @return system usage statistics