The lints.LintStatus type implements json.Marshaler to marshal to a human readable string (e.g. "error" instead of 6). Without providing a compatible json.Unmarshaler implementation downstream users that marshal a lints.LintStatus to JSON will encounter an error when they try to unmarshal it due to a mismatch of types (int vs string).

Notably this is causing me problems because when I added pre-issuance linting to CFSSL I made the configuration value on the cfssl.config.SigningProfile type a zlint.lints.LintStatus after a suggestion by the maintainers. That seemed fine at the time but I later discovered in Boulder we expect to be able to round-trip our CFSSL config to/from JSON without error.

Without the changes in this branch the de-serialization of the CFSSL config fails with an error like:

Failed to create CA: {"code":5200,"message":"failed to unmarshal configuration: json: cannot unmarshal string into Go struct field SigningProfile.lint_error_level of type lints.LintStatus"}