Fix resolve $refs in headers

Author: jorgerod

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/processors/ExternalRefProcessor.java

@@ -313,6 +313,9 @@ public PathItem processRefToExternalPathItem(String $ref, RefFormat refFormat) {
                                     if (response.getLinks() != null) {
                                         processRefLinks(response.getLinks(), $ref);
                                     }
+                                    if (response.getHeaders() != null) {
+                                        processRefHeaders(response.getHeaders(), $ref);
+                                    }
                                 }
                             }
                         }

modules/swagger-parser-v3/src/test/java/io/swagger/v3/parser/test/OpenAPIV3ParserTest.java

@@ -3476,4 +3476,16 @@ public void testIssue1902_component_example_not_parse_ordinal_json() {
         Example expectedExample = openAPI.getComponents().getExamples().get("Things");
         assertNotNull(expectedExample);
     }
+
+    @Test
+    public void testIssue_1746_headers_relative_paths() {
+        OpenAPIV3Parser openApiParser = new OpenAPIV3Parser();
+        ParseOptions options = new ParseOptions();
+        options.setResolve(true);
+        SwaggerParseResult parseResult = openApiParser.readLocation("issue-1746/petstore.yml", null, options);
+        OpenAPI openAPI = parseResult.getOpenAPI();
+
+
+        assertEquals(openAPI.getPaths().get("/pets").getGet().getResponses().get("200").getHeaders().get("x-next").get$ref(), "#/components/headers/LocationInHeaders");
+    }
 }

modules/swagger-parser-v3/src/test/resources/issue-1746/pets/def.yml

@@ -0,0 +1,45 @@
+components:
+  schemas:
+    Pet:
+      type: object
+      required:
+        - id
+        - name
+      properties:
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+        tag:
+          type: string
+    Pets:
+      type: array
+      items:
+        $ref: "#/components/schemas/Pet"
+    Error:
+      type: object
+      required:
+        - code
+        - message
+      properties:
+        code:
+          type: integer
+          format: int32
+        message:
+          type: string
+
+  links:
+    userRepository:
+      operationId: getRepository
+      requestBody: '$response.body#/slug'
+      headers:
+        X-Rate-Limit:
+          description: The number of allowed requests in the current period
+          schema:
+            type: integer
+  headers:
+    LocationInHeaders:
+      description: A link to the next page of responses
+      schema:
+        type: string

modules/swagger-parser-v3/src/test/resources/issue-1746/pets/pets.yml

@@ -0,0 +1,69 @@
+get:
+  summary: List all pets
+  operationId: listPets
+  tags:
+    - pets
+  parameters:
+    - name: myParam
+      in: query
+      description: Param
+      required: true
+      schema:
+        $ref: 'def.yml#/components/schemas/Pet'
+    - name: myParam2
+      in: query
+      description: Param2
+      required: true
+      schema:
+        $ref: './def.yml#/components/schemas/Pet'
+    - name: myParam3
+      in: query
+      description: Param3
+      required: true
+      schema:
+        $ref: '../pets/def.yml#/components/schemas/Pet'
+  responses:
+    "200":
+      description: A paged array of pets
+      headers:
+        x-next:
+          $ref: "./def.yml#/components/headers/LocationInHeaders"
+      content:
+        application/json:
+          schema:
+            $ref: "./def.yml#/components/schemas/Pets"
+    default:
+      description: unexpected error
+      content:
+        application/json:
+          schema:
+            $ref: "./def.yml#/components/schemas/Error"
+post:
+  summary: Create a pet
+  operationId: createPets
+  tags:
+    - pets
+  responses:
+    '201':
+      description: New guest added to event list
+      content:
+        application/json:
+          schema:
+            properties:
+              test:
+                type: string
+          examples:
+            testExamples:
+              $ref: "../petstore.yml#/components/schemas/DateWithExample"
+      links:
+        userRepository:
+          $ref: 'def.yml#/components/links/userRepository'
+    default:
+      description: unexpected error
+      content:
+        application/json:
+          schema:
+            $ref: "./def.yml#/components/schemas/Error"
+          example:
+            $ref: "../petstore.yml#/components/schemas/DateWithExample"
+

modules/swagger-parser-v3/src/test/resources/issue-1746/petstore.yml

@@ -0,0 +1,21 @@
+openapi: "3.0.0"
+info:
+  version: 1.0.0
+  title: Swagger Petstore
+  license:
+    name: MIT
+servers:
+  - url: http://petstore.swagger.io/v1
+paths:
+  /pets:
+    $ref: "./pets/pets.yml"
+
+components:
+  schemas:
+    Date:
+      type: string
+      format: date
+    DateWithExample:
+      $ref: '#/components/schemas/Date'
+      description: Date schema extended with a `default` value... Or not?
+      default: 2000-01-01