Class ParagraphTextValidationBuilder

// Add a paragraph text item to a form and require the answer to be at least 100
// characters.
const form = FormApp.create('My Form');
const paragraphTextItem =
    form.addParagraphTextItem().setTitle('Describe yourself:');
const paragraphtextValidation =
    FormApp.createParagraphTextValidation()
        .setHelpText('Answer must be more than 100 characters.')
        .requireTextLengthGreaterThan(100);
paragraphTextItem.setValidation(paragraphtextValidation);