Adding missing param filtering when visiting response headers
Adding the ability to serialize and XML payload even if no XML parameters were set.
Not adding default empty arrays or booleans when parsing XML that is not set. Now more consistent with the request JsonVisitor and API responses can more likely be reused as inputs.
Using union rather than merge when extending operations and adding tests. This has no effect other than speed improvements because when merging arrays where the key is a string, the last value overwrites the previous. However, this may fix edge cases where someone is defining arrays in their models for some reason.
Adding missing @throws tag
Preventing infinite recursion when resolving includes. Closes #255
Subtree splits need to have the correct branch alias.