It could be interesting to provide a custom codec that allows binding/getting JSON structures directly (using a popular API, probably Jackson):
Since JSON is not a primitive type in the native protocol, I imagine this will mean serializing it to strings (to check).
The pull request has support for two APIs: Jackson (JacksonJsonCodec) and JSR 353 (Jsr353JsonCodec), as well as an abstract codec that serializes from Java to text (StringParsingCodec).