currentDateAttributes is empty when using exposed date filter

When filtering on an indexed date field the process function doesn't have the right date attributes loaded to properly generate the time parts to create the timestamp.

  /**
   * {@inheritdoc}
   */
  protected function process(&$value) {
    if (is_numeric($value)) {
      $value = $this->processTimestamp($value, $this->currentDateAttributes);
    }
  }
}

The $this->currentDateAttributes is always blank and so the filtered value that goes to solr is always 0.

Instead it should load that specific field's date attributes.