An Any is populated with a union whose member is not empty.
Call dynAny->from_any (Any);
to put the Any'd union into a DynAny object.
Call dynAny->to_any () : Any
to get the Any'd union from a DynAny object.

Repeat the process except this time, use a union whose member is empty,
ie, _default () has been called on the union.

from_any (Any) succeeded.
to_any () : Any failed.

to_any () needs to check for an empty union before adding its member
to a CDR stream.