protected function setDefaultLastValue($attribute, $default)
{
if (empty($this->getLastValue()) && $this->getOperationType() == AttributeConverterInterface::TYPE_MODIFY) {
$original = $this->getCurrentLdapAttributeValue($attribute);
$this->setLastValue(is_null($original) ? $default : $original);
} elseif (empty($this->getLastValue()) && $this->getOperationType() == AttributeConverterInterface::TYPE_CREATE) {
$this->setLastValue($default);
}
}