A class like the following should cause an exception to be thrown at Schema instantiation time :

case class User(username: String, password: String, surname: String,
                  givenname: String, email: Option[String], phonenumber: Option[String], isEnabled: Boolean, rolename: String) extends KeyedEntity[String] {

 @Column("username")
 val id: String = username

 def this() = this("", "", "", "", Some(""), Some(""), false, "")
}