remove undefined properties instead of setting the {not: {}} type; do not add $descriptions for empty properties; slightly improve $ref type

Author: tatomyr

applications/__tests__/__snapshots__/e2e-bundle.test.js.snap

@@ -842,8 +842,6 @@ paths:
             schema:
               type: object
               properties:
-                id:
-                  not: {}
                 name:
                   type: object
                   properties:
@@ -979,17 +977,20 @@ paths:
                   $and:
                     - array: string
                     - array: number
+              examples:
+                Correct:
+                  value: {}
+                Incorrect:
+                  value:
+                    unexpected: fails
               schema:
                 type: object
-                properties:
-                  WrongAndFormat:
-                    not: {}
-                  Empty:
-                    not: {}
-                  ImpossibleArraysCombination:
-                    not: {}
+                properties: {}
                 required: []
                 additionalProperties: false
+            application/undefined+json:
+              x-type:
+                $and: []
 components:
   x-types:
     CorrectAnd:

applications/__tests__/__snapshots__/e2e-lint.test.js.snap

@@ -226,6 +226,7 @@ ERROR! Expected an array but got:
 { foo: 'boolean', bar: 'number' }
 ERROR! Cannot merge empty lists.
 ERROR! Cannot merge 'array' types.
+ERROR! Cannot merge empty lists.
 [1] applications/resources/openapi-and.yaml:16:17 at #/paths/~1test/get/responses/200/content/application~1json/example
 
 Example value must conform to the schema: must have required property 'bar'.
@@ -236,8 +237,8 @@ Example value must conform to the schema: must have required property 'bar'.
    |     ^^^^^^^^^^^
 17 |     wrong: not-expected!
    |     ^^^^^^^^^^^^^^^^^^^^
-18 |
-19 | application/problems+json:
+18 | application/problems+json:
+19 |   x-type:
 
 referenced from applications/resources/openapi-and.yaml:13:15 at #/paths/~1test/get/responses/200/content/application~1json 
 
@@ -252,8 +253,8 @@ Example value must conform to the schema: must NOT have additional properties \`
 16 |     foo: wrong!
 17 |     wrong: not-expected!
    |     ^^^^^
-18 |
-19 | application/problems+json:
+18 | application/problems+json:
+19 |   x-type:
 
 referenced from applications/resources/openapi-and.yaml:13:15 at #/paths/~1test/get/responses/200/content/application~1json 
 
@@ -264,37 +265,53 @@ Error was generated by the no-invalid-media-type-examples rule.
 
 Example value must conform to the schema: \`foo\` property type must be boolean.
 
-14 |   $ref: '#/components/x-types/CorrectAnd'
-15 | example:
-16 |   foo: wrong!
-   |        ^^^^^^
-17 |   wrong: not-expected!
-18 |
+14 |     $ref: '#/components/x-types/CorrectAnd'
+15 |   example:
+16 |     foo: wrong!
+   |          ^^^^^^
+17 |     wrong: not-expected!
+18 | application/problems+json:
 
 referenced from applications/resources/openapi-and.yaml:13:15 at #/paths/~1test/get/responses/200/content/application~1json 
 
 Error was generated by the no-invalid-media-type-examples rule.
 
 
-[4] applications/resources/openapi-and.yaml:23:21 at #/paths/~1test/get/responses/200/content/application~1problems+json/x-type/WrongAndFormat/$and
+[4] applications/resources/openapi-and.yaml:22:21 at #/paths/~1test/get/responses/200/content/application~1problems+json/x-type/WrongAndFormat/$and
 
 Expected type \`XTypeList\` (array) but got \`object\`
 
-21 | WrongAndFormat:
-22 |   $and: # Expected an array!
-23 |     foo: boolean
+20 | WrongAndFormat:
+21 |   $and: # Expected an array!
+22 |     foo: boolean
    |     ^^^^^^^^^^^^
-24 |     bar: number
+23 |     bar: number
    |     ^^^^^^^^^^^
-25 | Empty: # Cannot merge empty lists!
-26 |   $and: []
+24 | Empty: # Cannot merge empty lists!
+25 |   $and: []
 
 Error was generated by the spec rule.
 
 
+[5] applications/resources/openapi-and.yaml:35:21 at #/paths/~1test/get/responses/200/content/application~1problems+json/examples/Incorrect/value/unexpected
+
+Example value must conform to the schema: must NOT have additional properties \`unexpected\`.
+
+33 |     Incorrect:
+34 |       value:
+35 |         unexpected: fails
+   |         ^^^^^^^^^^
+36 | application/undefined+json:
+37 |   x-type:
+
+referenced from applications/resources/openapi-and.yaml:19:15 at #/paths/~1test/get/responses/200/content/application~1problems+json 
+
+Error was generated by the no-invalid-media-type-examples rule.
+
+
 applications/resources/openapi-and.yaml: validated in <test>ms
 
-❌ Validation failed with 4 errors.
+❌ Validation failed with 5 errors.
 run \`redocly lint --generate-ignore-file\` to add all problems to the ignore file.
 
 "
@@ -679,14 +696,14 @@ You have 1 warning.
 
 exports[`lint > openapi with writeOnly and readOnly fields 1`] = `
 "validating applications/resources/openapi-with-writeonly-and-readonly.yaml...
-[1] applications/resources/openapi-with-writeonly-and-readonly.yaml:21:23 at #/paths/~1test/get/requestBody/content/application~1json/examples/Incorrect/value/id
+[1] applications/resources/openapi-with-writeonly-and-readonly.yaml:21:19 at #/paths/~1test/get/requestBody/content/application~1json/examples/Incorrect/value/id
 
-Example value must conform to the schema: \`id\` property must NOT be valid.
+Example value must conform to the schema: must NOT have additional properties \`id\`.
 
 19 |         Incorrect:
 20 |           value:
 21 |             id: uuid-like-id # not expected in response
-   |                 ^^^^^^^^^^^^
+   |             ^^
 22 |             name: First Last # must be an object
 23 | responses:
 

applications/__tests__/adapter.test.js

@@ -18,7 +18,7 @@ describe('adapter', () => {
   })
 
   test('`undefined` -> `never`', () => {
-    expect(translateXTypeToSchema('undefined')).toEqual({not: {}})
+    expect(translateXTypeToSchema('undefined')).toEqual(undefined)
   })
 
   test('OR', () => {
@@ -32,9 +32,7 @@ describe('adapter', () => {
     expect(translateXTypeToSchema(['string', 'undefined'])).toEqual({
       type: 'string',
     })
-    expect(translateXTypeToSchema(['undefined'])).toEqual({
-      not: {},
-    })
+    expect(translateXTypeToSchema(['undefined'])).toEqual(undefined)
     expect(
       translateXTypeToSchema({
         Required: ['foo', 'number'],