Class GridValidationBuilder

// Add a grid item to a form and require one response per column.
var gridItem = form.addGridItem();
gridItem.setTitle('Rate your interests')
  .setRows(['Cars', 'Computers', 'Celebrities'])
  .setColumns(['Boring', 'So-so', 'Interesting']);
var gridValidation = FormApp.createGridValidation()
  .setHelpText(“Select one item per column.”)
  .requireLimitOneResponsePerColumn()
  .build();
gridItem.setValidation(gridValidation);