SplitkeyMin and SplitKeyMax is not working for isodate column

[bbnsumanth]

I'm using following config to read data using a splitkeyMin and Max.But whole data is getting loaded into dataframe.Im using latest version of spark-MonogDB and spark 2.0.0

val mongoConfig = MongodbConfigBuilder(
Map(
Credentials -> List(slaveCredentials),
Host -> mongoHost,
Database -> mongoDatabase,
Collection -> mongoCollection,
SamplingRatio -> 1.0,
WriteConcern -> "normal",
SplitSize -> "10",
SplitKey -> "created_at",
SplitKeyMin -> "2016-11-20T10:01:32.239Z",
SplitKeyMax -> "2016-11-23T10:01:32.239Z",
SplitKeyType -> "isoDate"
)
).build()

val mongoDF = spark.sqlContext.fromMongoDB(mongoConfig)

[bbnsumanth]

It is not working as there is no index on "created_at" field in my mongoCollection.
I would be very helpful if this is included in the documentation and also what is the format we must use in splitkeyMin/Max for isodate data type.