Property "description" not allowed (when it is $ref sibling)

[neopaf]

(thanks for very useful plugin!!)
version: 1.0.28

Input:

          "policyRuleSpec": {
            "$ref": "#/components/schemas/PolicyRuleSpecRef",
            "description": "some text"
          },

Intellij underlines description line red, suggests to remove it, and claims that

Property "description" not allowed.

I'm not sure who and how validates the document, status line has it "No JSON schema".

According to
https://swagger.io/docs/specification/using-ref/

All siblings of $ref must be ignored.

Is this message "not allowed" related to Swagger plugin?