What's new:
- Headers can be marked optional
- Stub data for multiple contracts can be loaded from a single directory.
- Sub types can now be stubbed out. E.g. if the contract says (string?), (string) and (null) can both be used in the stub data instead of literal values.
- Improved support for nullable keys and values in stub data
- A java helper method for setting up stubs with data
- A java helper to pick up a contract by specifying the major and minor version