/**
* Validate a user object.
*
* Invokes User::validate(),
* and additionally tests that the User's email address and username (if set) are unique across all users.'.
*
* @param User $user
* @return array An array of error messages, or an empty array if the User is valid.
*/
public function validate(AUser $user)
{
$errors = $user->validate();
// If username is required, ensure it is set.
if ($this->isUsernameRequired && !$user->getRealUsername()) {
$errors['username'] = '******';
}
return $errors;
}
