Swagger.yml: TypeError: Converting circular structure to JSON

Ran our swagger through this and saw the following error message:

https://apitools.dev/swagger-parser/online/?url=https%3A%2F%2Fraw.githubusercontent.com%2Finfluxdata%2Finfluxdb%2Fmaster%2Fhttp%2Fswagger.yml

```
This API is valid, but it cannot be shown because it contains circular references

TypeError: Converting circular structure to JSON
--> starting at object with constructor 'Object'
| property 'properties' -> object with constructor 'Object'
| property 'checks' -> object with constructor 'Object'
--- property 'items' closes the circle
at JSON.stringify ()
at toText (https://apitools.dev/swagger-parser/online/js/bundle.min.js:17:291033)
at Function.editors.addResult (https://apitools.dev/swagger-parser/online/js/bundle.min.js:17:292169)
at Function.editors.showResult (https://apitools.dev/swagger-parser/online/js/bundle.min.js:17:291450)
at https://apitools.dev/swagger-parser/online/js/bundle.min.js:17:295981
at Array.forEach ()
at https://apitools.dev/swagger-parser/online/js/bundle.min.js:17:295961
```

Open http/swagger.yml and inspect the properties.checks.items relationship reported by the Swagger Parser online URL. Confirm that the API definition no longer produces the circular-reference display error there.

Written by the indexing model from the issue text.