[EventGrid] Swagger ModelValidation INVALID_TYPE

[mikeharder]

Check Swagger ModelValidation is failing on EventGrid with this error:

##[error]Validating "examples" and "x-ms-examples" in  specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/EventGrid.json:
 error : 
code: INVALID_TYPE
message: Expected type  but found type object
schemaUrl: >-
  specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/EventGrid.json
exampleUrl: >-
  specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/examples/publish.json
schemaPosition:
  line: 82
  column: 22
schemaJsonPath: !<tag:yaml.org,2002:js/undefined> ''
examplePosition:
  line: 24
  column: 16
exampleJsonPath: $response.200/body
severity: 0
source: response
operationId: PublishCloudEvents
level: error

https://github.com/Azure/azure-rest-api-specs/pull/25323/checks?check_run_id=15930723858

From @johanste:

It looks to me like validation of examples of APIs that return an empty object may be incorrect. There is (or at least was) some ambiguity between not returning anything and returning an empty object in x-ms-examples. For the longest time it didn't matter, but at some point it was decided by the REST API review board that returning nothing was bad and empty object preferred.

I believe this behavior is coded here:

https://github.com/Azure/oav/blob/760a3352a04ebfcd2e9a1d05c7ad4925f20caa2c/lib/swaggerValidator/modelValidator.ts#L744

[l0lawrence]

#25387

[mikeharder]

#25387

Attempted fix, rejected until we better understand the issue.

[mikeharder]

I searched for similar specs in the repo, and what I found was interesting. Here is the swagger and example for Cdn@2017-10-12:

azure-rest-api-specs/specification/cdn/resource-manager/Microsoft.Cdn/stable/2017-10-12/cdn.json

Lines 1562 to 1565 in 1d2b8c0

	"responses": {
	"200": {
	"description": "OK. The request has succeeded."
	},

azure-rest-api-specs/specification/cdn/resource-manager/Microsoft.Cdn/stable/2017-10-12/examples/CustomDomains_Delete.json

Lines 10 to 14 in 1d2b8c0

	"responses": {
	"200": {
	"body": {}
	}
	}

In Cdn@2019-04-15, the swagger is unchanged, but the example response is changed from "200": { "body": { } } to "200": { }:

azure-rest-api-specs/specification/cdn/resource-manager/Microsoft.Cdn/stable/2019-04-15/cdn.json

Lines 1562 to 1565 in 1d2b8c0

	"responses": {
	"200": {
	"description": "OK. The request has succeeded."
	},

azure-rest-api-specs/specification/cdn/resource-manager/Microsoft.Cdn/stable/2019-04-15/examples/CustomDomains_Delete.json

Lines 10 to 12 in 1d2b8c0

	"responses": {
	"200": {},
	"202": {

Here are the swagger and example for EventGrid@2023-06-01:

azure-rest-api-specs/specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/EventGrid.json

Lines 82 to 88 in 1d2b8c0

	"responses": {
	"200": {
	"description": "The request has succeeded.",
	"schema": {
	"$ref": "#/definitions/PublishResult"
	}
	},

azure-rest-api-specs/specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/EventGrid.json

Lines 554 to 558 in 1d2b8c0

	"PublishResult": {
	"type": "object",
	"description": "The result of the Publish operation.",
	"properties": {}
	},

azure-rest-api-specs/specification/eventgrid/data-plane/Microsoft.EventGrid/preview/2023-06-01-preview/examples/publish.json

Lines 24 to 28 in 1d2b8c0

	"responses": {
	"200": {
	"body": {}
	}
	}

@johanste, @l0lawrence: Given these examples, do you still think check Swagger ModelValidation is reporting a false positive for EventGrid? Meaning Swagger ModelValidation should be updated so the above EventGrid swagger and example is not a violation?

Or perhaps the EventGrid example should be changed from "200": { "body": { } } to "200": { }, like how the Cdn sample was changed between the two versions?