As mentioned in this comment in CASSANDRA-10365, the current implementations of AbstractType.getString/TypeSerializer.toString don't work as expected and do not generate valid CQL terms as needed by CASSANDRA-10365.
is blocked by
CASSANDRA-10365Store types by their CQL names in schema tables instead of fully-qualified internal class names
Is contained by
CASSANDRA-10650Store UDA initcond as CQL literal in the schema table, instead of a blob