[SPARK-13121][STREAMING] java mapWithState mishandles scala Option

Already merged into 1.6 branch, this PR is to commit to master the same change

Author: Gabriele Nizzoli <mail@nizzoli.net>

Closes #11028 from gabrielenizzoli/patch-1.

streaming/src/main/scala/org/apache/spark/streaming/StateSpec.scala

@@ -221,7 +221,7 @@ object StateSpec {
       mappingFunction: JFunction3[KeyType, Optional[ValueType], State[StateType], MappedType]):
     StateSpec[KeyType, ValueType, StateType, MappedType] = {
     val wrappedFunc = (k: KeyType, v: Option[ValueType], s: State[StateType]) => {
-      mappingFunction.call(k, Optional.ofNullable(v.get), s)
+      mappingFunction.call(k, JavaUtils.optionToOptional(v), s)
     }
     StateSpec.function(wrappedFunc)
   }