The <cxxStructBaseUnion> element declares inheritance from a base union in a struct derivation.
Used within a <cxxStructDerivation> element to declare inheritance from a base union.
<cxxStructDerivation>
<cxxStructDerivationAccessSpecifier value="public"/>
<cxxStructBaseUnion href="union_base">Base</cxxStructBaseUnion>
</cxxStructDerivation>