public function equals(AttributeTypeAndValue $other): bool
    {
        // check that attribute types match
        if ($this->oid() !== $other->oid()) {
            return false;
        }
        $matcher = $this->_value->equalityMatchingRule();
        $result = $matcher->compare($this->_value->stringValue(),
            $other->_value->stringValue());
        // match
        if ($result) {
            return true;
        }
        // no match or Undefined
        return false;
    }