code: public Map<String, String> getObjectScalar(TableDefinition    tableDef,
                                                 Collection<String> objIDs,
                                                 String             fieldName) {
          checkServiceState();
          Map<String, String> objScalarMap = new HashMap<>();
          Tenant tenant = Tenant.getTenant(tableDef);
          if (objIDs.size() > 0) {
              String storeName = objectsStoreName(tableDef);
              for(DRow row: DBService.instance(tenant).getRows(storeName, objIDs)) {
                  DColumn col = row.getColumn(fieldName);
                  if (col != null) {
                      String fieldValue = scalarValueToString(tableDef, col.getName(), col.getRawValue());
                      objScalarMap.put(row.getKey(), fieldValue);
                  }
              }
          }
          return objScalarMap;
      }
docs: Retrieve a single scalar field for the given object IDs in the given table.
  The map returned is object IDs -> field value. The map will be empty (but not null)
  if objIDs is empty or none of the requested object IDs have a value for the
  requested field name.
  
  @param tableDef      {@link TableDefinition} of table to query.
  @param objIDs        Collection of object IDs to fetch.
  @param fieldName     Scalar field name to get values for.
  @return              Map of object IDs -> field values for values found.