protected function getSelectedQueryAttributes(array $attributes, LdapObjectSchema $schema = null)
{
// Interpret a single wildcard as only schema attributes.
if ($schema && !empty($attributes) && $attributes[0] == '*') {
$attributes = array_keys($schema->getAttributeMap());
// Interpret a double wildcard as all LDAP attributes even if they aren't in the schema file.
} elseif ($schema && !empty($attributes) && $attributes[0] == '**') {
$attributes = ['*'];
}
return $attributes;
}