This looks cool, but I'm also interested in seeing if compared to GSON not just Jackson. Is the `JsonField` annotation mandatory? In most cases my variable names are the same as the field names in the JSON, which is why I love using GSON since it auto-picks up on that.

It looks kind of odd in your sample code too, it'd be nice if it could auto-try those fields, but I can see why that won't work if this is compile-time rather than at processing-time like GSON (it has no way of checking against the JSON to see if that assumption is true) -- maybe have `JsonType` take and optional parameter that enables "guess types" mode?