Casting nested Scala collections to Cassandra types using Alpakka Cassandra

Hi, I’m trying to use akka-stream-alpakka-cassandra for writing steam data to a Cassandra table. The table definition has a field of type: list<frozen<tuple<text, int>>>. Unfortunately I can declare the value in the case class of List[(String, Text)].
I’m getting the error: Unable to process data stream. Exception: java.lang.ClassCastException: scala.collection.immutable.$colon$colon cannot be cast to com.datastax.oss.driver.api.core.type.ListType
Do you guys know how can I covert Scala collections to Datastax collection type?
Another solution is to wrap the tuple into a Cassandra type (object) and define some enconding / decodings. Do you guys have an example on how I can do this?