Add openapi-normalizer rule to set tags to vendor extension

docs/customization.md

@@ -573,6 +573,13 @@ Example:
 java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g java -i modules/openapi-generator/src/test/resources/3_0/petstore.yaml -o /tmp/java-okhttp/ --openapi-normalizer SET_TAGS_TO_OPERATIONID=true
 ```
 
+- `SET_TAGS_TO_VENDOR_EXTENSION`:  when set to a string value, tags will be set to the value of the provided vendor extension
+
+Example:
+```
+java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g java -i modules/openapi-generator/src/test/resources/3_0/enableSetTagsToVendorExtension_test.yaml -o /tmp/java-okhttp/ --openapi-normalizer SET_TAGS_TO_VENDOR_EXTENSION=x-tags
+```
+
 - `ADD_UNSIGNED_TO_INTEGER_WITH_INVALID_MAX_VALUE`: when set to true, auto fix integer with maximum value 4294967295 (2^32-1) or long with 18446744073709551615 (2^64-1) by adding x-unsigned to the schema
 
 Example:

modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java

@@ -91,6 +91,10 @@ public class OpenAPINormalizer {
     final String SET_TAGS_TO_OPERATIONID = "SET_TAGS_TO_OPERATIONID";
     String setTagsToOperationId;
 
+    // when set to a string value, tags will be set to the value of the provided vendor extension
+    final String SET_TAGS_TO_VENDOR_EXTENSION = "SET_TAGS_TO_VENDOR_EXTENSION";
+    String setTagsToVendorExtension;
+
     // when set to true, tags in all operations will be set to operationId or "default" if operationId
     // is empty
     final String FIX_DUPLICATED_OPERATIONID = "FIX_DUPLICATED_OPERATIONID";
@@ -158,6 +162,7 @@ public OpenAPINormalizer(OpenAPI openAPI, Map<String, String> inputRules) {
         ruleNames.add(KEEP_ONLY_FIRST_TAG_IN_OPERATION);
         ruleNames.add(SET_TAGS_FOR_ALL_OPERATIONS);
         ruleNames.add(SET_TAGS_TO_OPERATIONID);
+        ruleNames.add(SET_TAGS_TO_VENDOR_EXTENSION);
         ruleNames.add(FIX_DUPLICATED_OPERATIONID);
         ruleNames.add(ADD_UNSIGNED_TO_INTEGER_WITH_INVALID_MAX_VALUE);
         ruleNames.add(REFACTOR_ALLOF_WITH_PROPERTIES_ONLY);
@@ -224,6 +229,11 @@ public void processRules(Map<String, String> inputRules) {
             rules.put(SET_TAGS_FOR_ALL_OPERATIONS, true);
         }
 
+        setTagsToVendorExtension = inputRules.get(SET_TAGS_TO_VENDOR_EXTENSION);
+        if (setTagsToVendorExtension != null) {
+            rules.put(SET_TAGS_TO_VENDOR_EXTENSION, true);
+        }
+
         if (inputRules.get(FILTER) != null) {
             rules.put(FILTER, true);
 
@@ -375,6 +385,8 @@ private void normalizeOperation(Operation operation) {
 
         processSetTagsToOperationId(operation);
 
+        processSetTagsToVendorExtension(operation);
+
         processFixDuplicatedOperationId(operation);
     }
 
@@ -885,8 +897,7 @@ private void processUseAllOfRefAsParent(Schema schema) {
     }
 
     /**
-     * Keep only first tag in the operation if the operation has more than
-     * one tag.
+     * Remove/hide the x-internal in operations and model.
      *
      * @param operation Operation
      */
@@ -955,6 +966,34 @@ private void processSetTagsToOperationId(Operation operation) {
         }
     }
 
+    /**
+     * Set the tag name to the value of the provided vendor extension
+     *
+     * @param operation Operation
+     */
+    private void processSetTagsToVendorExtension(Operation operation) {
+        if (StringUtils.isEmpty(setTagsToVendorExtension)) {
+            return;
+        }
+
+        if (operation.getExtensions() == null) {
+            return;
+        }
+
+        if (operation.getExtensions().containsKey(setTagsToVendorExtension)) {
+            operation.setTags(null);
+            Object argObj = operation.getExtensions().get(setTagsToVendorExtension);
+            if (argObj instanceof List) {
+                List<String> tags = (List<String>) argObj;
+                for (String tag : tags) {
+                    operation.addTagsItem(tag);
+                }
+            } else {
+                operation.addTagsItem(String.valueOf(argObj));
+            }
+        }
+    }
+
     private void processFixDuplicatedOperationId(Operation operation) {
         if (!getRule(FIX_DUPLICATED_OPERATIONID)) {
             return;

modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java

@@ -294,6 +294,21 @@ public void testOpenAPINormalizerSetTagsToOperationId() {
         assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getTags().get(0), "delete");
     }
 
+    @Test
+    public void testOpenAPINormalizerSetTagsToVendorExtension() {
+        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/enableSetTagsToVendorExtension_test.yaml");
+
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 2);
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getExtensions().size(), 1);
+
+        Map<String, String> options = new HashMap<>();
+        options.put("SET_TAGS_TO_VENDOR_EXTENSION", "x-tags");
+        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
+        openAPINormalizer.normalize();
+
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getTags().size(), 1);
+    }
+
     @Test
     public void testAddUnsignedToIntegerWithInvalidMaxValue() {
         OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/addUnsignedToIntegerWithInvalidMaxValue_test.yaml");

modules/openapi-generator/src/test/resources/3_0/enableSetTagsToVendorExtension_test.yaml

@@ -0,0 +1,43 @@
+openapi: 3.0.1
+info:
+  version: 1.0.0
+  title: Example
+  license:
+    name: MIT
+servers:
+  - url: http://api.example.xyz/v1
+paths:
+  /person/display/{personId}:
+    get:
+      x-tags:
+        - display
+      tags:
+        - person
+        - basic
+      parameters:
+        - name: personId
+          in: path
+          required: true
+          description: The id of the person to retrieve
+          schema:
+            type: string
+      operationId: list
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Person"
+components:
+  schemas:
+    Person:
+      description: person
+      type: object
+      properties:
+        $_type:
+          type: string
+        lastName:
+          type: string
+        firstName:
+          type: string