Results

   *   The formatted RFC3339 date string or UNIX timestamp.
   *
   * @see \Drupal\serialization\Normalizer\TimestampItemNormalizer
   */
  protected function formatExpectedTimestampItemValues($timestamp) {
    // Get the minor version only from the \Drupal::VERSION string.
    $minor_version = substr(\Drupal::VERSION, 0, 3);

    // If the setting is enabled, just return the timestamp as-is now.

    // Otherwise, format the date string to the same that
    // \Drupal\serialization\Normalizer\TimestampItemNormalizer will produce.
    $date = new \DateTime();
    $date->setTimestamp($timestamp);
    $date->setTimezone(new \DateTimeZone('UTC'));

    // Format is also added to the expected return values.
    return [

use Drupal\Core\TypedData\Plugin\DataType\Timestamp;

use Drupal\serialization\Normalizer\TimestampItemNormalizer as BaseTimestampItemNormalizer;

/**
 * Converts values for TimestampItem to and from common formats.
 *
 * Overrides FieldItemNormalizer and
 * \Drupal\serialization\Normalizer\TimestampNormalizer

namespace Drupal\smart_date\Normalizer;

use Drupal\serialization\Normalizer\TimestampItemNormalizer;
use Drupal\smart_date\Plugin\Field\FieldType\SmartDateItem;
use Drupal\smart_date\TypedData\Plugin\DataType\SmartDate;

/**
 * Converts values for TimestampItem to and from common formats.
 *