Update OptionDeserializerModule.scala

Author: pjfanning

src/main/scala/tools/jackson/module/scala/deser/OptionDeserializerModule.scala

@@ -19,6 +19,7 @@ private class OptionDeserializer(fullType: JavaType,
 
   override def getValueType: JavaType = fullType
 
+  override def getEmptyValue(ctxt: DeserializationContext): Option[AnyRef] = None
   override def getNullValue(ctxt: DeserializationContext): Option[AnyRef] = None
 
   private[this] def withResolved(fullType: JavaType,