public function validateForUsage($sourceObject, $propertiesToSkip = array())
 {
     parent::validateForUsage($sourceObject, $propertiesToSkip);
     $this->validatePropertyNotNull('xPath');
     $this->validatePropertyNotNull('versionA');
     $this->validatePropertyNotNull('versionB');
     $this->validatePropertyNotNull(array('profileId', 'profileSystemName'));
 }