Nullable enum warning for null value in example section

[sergle]

I receive warning when trying to use null value in example section for property with enum.

To Reproduce

1. Given this OpenAPI/AsyncAPI document:
   nullable_enum.yaml

2. Run this CLI command:

spectral lint -v nullable_enum.yaml

3. See error

Found 82 rules (66 enabled)
Linting nullable_enum.yaml
OpenAPI 3.x detected

nullable_enum.yaml
39:23 warning typed-enum Enum value null does not respect the specified type string.
✖ 1 problem (0 errors, 1 warning, 0 infos, 0 hints)

Expected behavior
No warnings produced

Environment:

• Library version: 5.5.0
• OS: Debian 9 (image node:14.11-slim from Docker Hub)

Additional context
FROM node:14.11-slim
RUN yarn global add @stoplight/spectral
ADD nullable_enum.yaml nullable_enum.yaml
RUN spectral lint -v nullable_enum.yaml

[philsturgeon]

Do you even need to have that null in there? Isn't that redundant?

[sergle]

Yes, it's redundant. But I'm trying to document existing API which is already used in such way.

[philsturgeon]

OpenAPI wouldn’t care unless... are you trying to have a literal null or a string which is a “null”? If the API is spitting out “null” then you cannot use nullable: true.

[sergle]

A literal null.

[philsturgeon]

Ok so when you’ve removed it from the OpenAPI description, how does Spectral behave? It’s one less thing for us to worry about and as it’s literally redundant it doesn’t need to be there. If it’s still broke we can look into it.

[sergle]

When I remove result:null from example, output is:

Found 82 rules (66 enabled)
Linting /tmp/nullable_enum.yaml
OpenAPI 3.x detected

/tmp/nullable_enum.yaml
39:23 warning typed-enum Enum value null does not respect the specified type string.

✖ 1 problem (0 errors, 1 warning, 0 infos, 0 hints)

When I remove null from enum values, output is:

Found 82 rules (66 enabled)
Linting /tmp/nullable_enum.yaml
OpenAPI 3.x detected

/tmp/nullable_enum.yaml
41:25 error oas3-valid-schema-example result property should be equal to one of the allowed values: OK, FAILED

✖ 1 problem (1 error, 0 warnings, 0 infos, 0 hints)

When I remove both result:null and null from enum values, no problem found.