Laravel 5.2 reset password with another column name (not email)

I'm taking over a project from the other, the old database schema uses "username" instead of "email". It causes the conflict when I add reset password functionality.

public function getEmailForPasswordReset()
{
    return $this->email;
}

Is there some way to customize that trait to use another column name over "email"?

via Chebli Mohamed