TODO.md in openapi3_parser-0.1.0 vs TODO.md in openapi3_parser-0.2.0

@@ -26,5 +26,6 @@
 - [ ] Associate/resolve operation id / operation references
 - [ ] Do something to model expressions
 - [ ] Improve the modelling of namespace
 - [ ] Set up nicer string representations of key classes to help them be
       debugged
+- [ ] Ensure Array and Map nodes return empty ones by default rather than nil