Customer is experiencing a duplicate key exception when attempting to execute MongoSpark.save(RDD, writeConfig)

def save[D: ClassTag](rdd: RDD[D], writeConfig: WriteConfig): Unit)and encountering documents which already exist in the target collection (same _id)

Looking at MongoSpark.scala, it appears that there is a code path for

def save[D](dataset: Dataset[D], writeConfig: WriteConfig): Unit

that checks for the option replaceDocument This check isn't contained in the RDD code path.

Can this be added? Is there a specific reason this is disallowed? Are there other workarounds for this?