Function isRequired

packages/ra-core/src/form/validation/validate.ts:326–334

 * Given a validator, returns a boolean indicating whether the field is required or not.
 */
export const isRequired = validate => {
    if (validate && validate.isRequired) {
        return true;
    }
    if (Array.isArray(validate)) {
        return !!validate.find(it => it.isRequired);
    }
    return false;
};