Problem: missing automatic code generation for json

all json data can be represented with automatically generated go files from proto files.
replace class with these classes will be minimal side-effect.

because it's automatically generated, correctness is guaranteed.
also work productivity is much better when adding new events

can go to Protobuf easily, for future enhancements

No files, tests, or entry points are named. Locate the current JSON event classes and the proto definitions, then determine the migration scope; done means the JSON data is represented by generated Go files without regressions.

Written by the indexing model from the issue text.