[YCQL] Support UDTs referring to other frozen UDTs

[frozenspider]

Cassandra CQL allows user-defined types to refer to other user-defined types (only frozen though), YCQL should allow the same thing.

CQL:

cqlsh> CREATE TYPE k.t2(i int, t k.t1);
InvalidRequest: Error from server: code=2200 [Invalid query] message="A user type cannot contain non-frozen UDTs"

cqlsh> CREATE TYPE k.t2(i int, t frozen<k.t1>);
# Works fine

YCQL:

cqlsh> CREATE TYPE k.t2(i int, t k.t1);
SyntaxException: Feature Not Supported. UDT field types cannot refer to other user-defined types
CREATE TYPE k.t2(i int, t k.t1);
                        ^
 (error -14)

cqlsh> CREATE TYPE k.t2(i int, t frozen<k.t1>);
SyntaxException: Feature Not Supported. UDT field types cannot refer to other user-defined types
CREATE TYPE k.t2(i int, t frozen<k.t1>);
                        ^
 (error -14)

[robinbraemer]

I want this feature get supported.

[m-iancu]

This is now allowed as long as the internal UDT is frozen (same as in vanilla Cassandra above).

ycqlsh> create keyspace k;
ycqlsh> use k;
ycqlsh:k> create type t1(a int);
ycqlsh:k> create type t2(i int, j t1);
SyntaxException: Feature Not Supported. A user-defined type cannot contain non-frozen UDTs
create type t2(i int, j t1);
                      ^
 (ql error -14)
ycqlsh:k> create type t2(i int, j frozen<t1>);
ycqlsh:k>