in Spark Streaming, java mapWithState that uses Function3 has a bug in the convertion from a scala Option to a java Optional. In the conversion, the code in `StateSpec.scala`, line 222 is
`Optional.fromNullable(v.get)`. This fails if `v`, an `Option`, is `None`, better to use `JavaUtils.optionToOptional(v)` instead.
Workaround is to use the Function4 call to mapWithState. This call has the right conversion.