CommerceGuys\Addressing\AddressFormat\AddressFormat::getRequiredFields PHP Method

    public function getRequiredFields()
    {
        return $this->requiredFields;
    }

 /**
  * Validates the provided field values.
  *
  * @param array         $values        The field values, keyed by field constants.
  * @param AddressFormat $addressFormat The address format.
  * @param Constraint    $constraint    The constraint.
  */
 protected function validateFields($values, AddressFormat $addressFormat, $constraint)
 {
     // Validate the presence of required fields.
     $requiredFields = $addressFormat->getRequiredFields();
     foreach ($requiredFields as $field) {
         if (empty($values[$field]) && in_array($field, $constraint->fields)) {
             $this->addViolation($field, $constraint->notBlankMessage, $values[$field], $addressFormat);
         }
     }
     // Validate the absence of unused fields.
     $unusedFields = array_diff(AddressField::getAll(), $addressFormat->getUsedFields());
     foreach ($unusedFields as $field) {
         if (!empty($values[$field]) && in_array($field, $constraint->fields)) {
             $this->addViolation($field, $constraint->blankMessage, $values[$field], $addressFormat);
         }
     }
 }