public function fieldSettingsToHash($fieldSettings)
{
$fieldSettingsHash = parent::fieldSettingsToHash($fieldSettings);
if (isset($fieldSettingsHash['dateInterval'])) {
$fieldSettingsHash['dateInterval'] = $fieldSettingsHash['dateInterval']->format('P%r%yY%r%mM%r%dDT%r%hH%iM%r%sS');
}
return $fieldSettingsHash;
}