@classmethod<EOL><INDENT>def get_ns3_spec_for_union(cls):<DEDENT>
return cls._ns3_union_spec<EOL>
Returns a test namespace which has a union field with all possible types of
members a union can have. It includes (1) primitive, (2) struct, (3) enumerated
subtypes, and (4) a union. This spec is useful in validating the auto-generated
code for a union type defined in a namespace.