ExternalSender::getSenderFromSubject

private function getSenderFromSubject($subject): Result
{
	$cascadeResult = new Result();
	if (is_numeric($subject))
	{
		$cascadeResult = $this->utils->getCascadeIdFromSubject(
			(int)$subject,
			static function(array $externalSubjectData, int $internalSubject)
			{
				return $externalSubjectData['id'] === $internalSubject;
			}
		);
	}
	elseif (is_string($subject))
	{
		$cascadeResult = $this->utils->getCascadeIdFromSubject(
			$subject,
			static function(array $externalSubjectData, string $internalSubject)
			{
				return $externalSubjectData['subject'] === $internalSubject;
			}
		);
	}
	else
	{
		$cascadeResult->addError(new Error('Invalid subject id'));
	}

	return $cascadeResult;
}