code: @Override
      @Nullable
      public Constant getConstant(int column) throws OntopResultConversionException {
          final MainTypeLangValues cell = row.get(column - 1);
          if (cell.getMainValue() == null) {
              return null;
          } else {
              return constantRetriever.getConstantFromJDBC(cell);
          }
      }
docs: *
  Returns the constant at column "column". Recall that columns start at index 1.