in bijection-finagle-mysql/src/main/scala/com/twitter/bijection/finagle_mysql/MySqlConversions.scala [104:110]
def apply(n: EmptyValue.type) = None
override def invert(n: Option[A]) =
n match {
case Some(_) =>
Failure(new RuntimeException("Cannot convert non-empty option to EmptyValue"))
case None => Success(EmptyValue)
}