Transient Replication is an experimental feature being introduced in Cassandra 4.0.
When specifying replication options using transient replication, the user specifies the total number of replicas and how many are transient for the replication factor, i.e.:
In this case the replication factor is defined as 3 with 1 being transient.
The driver currently assumes that this value is an int, as that has always been the case. Because of this, the ReplicationStrategy instance can not be built for keyspace metadata:
Fortunately, the KeyspaceMetadata instance is still constructed and the driver seems to handle the case where replication strategy is null.
It would be nice if we were capable of parsing this. There might also be other considerations, like how transient replicas should be factored as it pertains to token aware routing.