Cassandra Driver 4.x null Metadata in Scala

I used Cassandra Datastax driver 4.x in Scala. I build a minimal session as Datastax explain in its documentation:

ref. https://github.com/datastax/java-driver/tree/4.x/manual/core#cqlsession

val session: CqlSession = CqlSession.builder.build()

I have few keyspaces and tables in my cassandra instance (apache cassandra 3.11). However, when I try to get all keyspaces by getMetadata method, it returns an empty list.

val keyspaces = session.getMetadata.getKeyspaces.values()

Does anyone have the same problem or know what happens here?

Thanks so much!