Class CheckboxGridValidation

// Add a checkbox grid item to a form and require one response per column. const form = FormApp.openById('123abc'); const checkboxGridItem = form.addCheckboxGridItem(); checkboxGridItem.setTitle('Where did you celebrate New Years?')     .setRows(['New York', 'San Francisco', 'London'])     .setColumns(['2014', '2015', '2016', '2017']); const checkboxGridValidation = FormApp.createCheckboxGridValidation()                                    .setHelpText('Select one item per column.')                                    .requireLimitOneResponsePerColumn()                                    .build(); checkboxGridItem.setValidation(checkboxGridValidation);