/**
* @param string $subject
* @return null
*/
public function setSubject($subject)
{
if (!isset($this->loadedFields['subject'])) {
$this->loadProperties();
}
$oldValue = null;
if (array_key_exists('subject', $this->loadedValues)) {
$oldValue = $this->loadedValues['subject'];
}
if ($oldValue === $subject) {
$this->subject = $subject;
return;
}
return parent::setSubject($subject);
}
