Class GridValidationBuilder

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