Add rule to set container (array, set, map) to true

docs/customization.md

@@ -598,3 +598,10 @@ 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 FILTER="operationId:addPet|getPetById"
 ```
+
+- `SET_CONTAINER_TO_NULLABLE`: When set to `array|set|map` (or just `array`) for example, it will set `nullable` in array, set and map to true.
+
+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_CONTAINER_TO_NULLABLE="array|map"
+```

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

@@ -101,10 +101,17 @@ public class OpenAPINormalizer {
     final String X_INTERNAL = "x-internal";
     boolean removeXInternal;
 
-    // when set (e.g. operationId:getPetById, addPet), filter out (or remove) everything else
+    // when set (e.g. operationId:getPetById|addPet), filter out (or remove) everything else
     final String FILTER = "FILTER";
     HashSet<String> operationIdFilters = new HashSet<>();
 
+    // when set (e.g. operationId:getPetById|addPet), filter out (or remove) everything else
+    final String SET_CONTAINER_TO_NULLABLE = "SET_CONTAINER_TO_NULLABLE";
+    HashSet<String> setContainerToNullable = new HashSet<>();
+    boolean updateArrayToNullable;
+    boolean updateSetToNullable;
+    boolean updateMapToNullable;
+
     // ============= end of rules =============
 
     /**
@@ -199,6 +206,23 @@ public void processRules(Map<String, String> inputRules) {
                 }
             }
         }
+
+        if (inputRules.get(SET_CONTAINER_TO_NULLABLE) != null) {
+            rules.put(SET_CONTAINER_TO_NULLABLE, true);
+            setContainerToNullable = new HashSet<>(Arrays.asList(inputRules.get(SET_CONTAINER_TO_NULLABLE).split("[|]")));
+            if (setContainerToNullable.contains("array")) {
+                updateArrayToNullable = true;
+            }
+            if (setContainerToNullable.contains("set")) {
+                updateSetToNullable = true;
+            }
+            if (setContainerToNullable.contains("map")) {
+                updateMapToNullable = true;
+            }
+            if (!updateArrayToNullable && !updateSetToNullable && !updateMapToNullable) {
+                LOGGER.error("SET_CONTAINER_TO_NULLABLE rule must be in the form of `array|set|map`, e.g. `set`, `array|map`: {}", inputRules.get(SET_CONTAINER_TO_NULLABLE));
+            }
+        }
     }
 
     /**
@@ -445,8 +469,10 @@ public Schema normalizeSchema(Schema schema, Set<Schema> visitedSchemas) {
         }
 
         if (schema instanceof ArraySchema) { // array
+            normalizeArraySchema(schema);
             normalizeSchema(schema.getItems(), visitedSchemas);
         } else if (schema.getAdditionalProperties() instanceof Schema) { // map
+            normalizeMapSchema(schema);
             normalizeSchema((Schema) schema.getAdditionalProperties(), visitedSchemas);
         } else if (ModelUtils.isOneOf(schema)) { // oneOf
             return normalizeOneOf(schema, visitedSchemas);
@@ -498,6 +524,14 @@ public Schema normalizeSchema(Schema schema, Set<Schema> visitedSchemas) {
         return schema;
     }
 
+    private Schema normalizeArraySchema(Schema schema) {
+        return processSetArraytoNullable(schema);
+    }
+
+    private Schema normalizeMapSchema(Schema schema) {
+        return processSetMapToNullable(schema);
+    }
+
     private Schema normalizeSimpleSchema(Schema schema, Set<Schema> visitedSchemas) {
         return processNormalize31Spec(schema, visitedSchemas);
     }
@@ -864,6 +898,60 @@ private Schema processSimplifyOneOf(Schema schema) {
         return schema;
     }
 
+    /**
+     * Set nullable to true in array/set if needed.
+     *
+     * @param schema Schema
+     * @return Schema
+     */
+    private Schema processSetArraytoNullable(Schema schema) {
+        if (!getRule(SET_CONTAINER_TO_NULLABLE)) {
+            return schema;
+        }
+
+        if (Boolean.TRUE.equals(schema.getUniqueItems())) { // a set
+            if (updateSetToNullable) {
+                if (schema.getNullable() != null || (schema.getExtensions() != null && schema.getExtensions().containsKey("x-nullable"))) {
+                    // already set, don't overwrite
+                    return schema;
+                }
+                schema.setNullable(true);
+            }
+        } else { // array
+            if (updateArrayToNullable) {
+                if (schema.getNullable() != null || (schema.getExtensions() != null && schema.getExtensions().containsKey("x-nullable"))) {
+                    // already set, don't overwrite
+                    return schema;
+                }
+                schema.setNullable(true);
+            }
+        }
+
+        return schema;
+    }
+
+    /**
+     * Set nullable to true in map if needed.
+     *
+     * @param schema Schema
+     * @return Schema
+     */
+    private Schema processSetMapToNullable(Schema schema) {
+        if (!getRule(SET_CONTAINER_TO_NULLABLE)) {
+            return schema;
+        }
+
+        if (updateMapToNullable) {
+            if (schema.getNullable() != null || (schema.getExtensions() != null && schema.getExtensions().containsKey("x-nullable"))) {
+                // already set, don't override
+                return schema;
+            }
+            schema.setNullable(true);
+        }
+
+        return schema;
+    }
+
     /**
      * If the schema is anyOf and the sub-schemas is null, set `nullable: true` instead.
      * If there's only one sub-schema, simply return the sub-schema directly.

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

@@ -475,4 +475,42 @@ public void testComposedSchemaDoesNotThrow() {
         OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, Collections.emptyMap());
         openAPINormalizer.normalize();
     }
+
+    @Test
+    public void testSetContainerToNullable() {
+        // test `array|map`
+        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/setContainerToNullable_test.yaml");
+
+        Schema schema = openAPI.getComponents().getSchemas().get("Person");
+        assertEquals(((Schema) schema.getProperties().get("array_property")).getNullable(), null);
+        assertEquals(((Schema) schema.getProperties().get("set_property")).getNullable(), null);
+        assertEquals(((Schema) schema.getProperties().get("map_property")).getNullable(), null);
+
+        Map<String, String> options = new HashMap<>();
+        options.put("SET_CONTAINER_TO_NULLABLE", "array|map");
+        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
+        openAPINormalizer.normalize();
+
+        Schema schema2 = openAPI.getComponents().getSchemas().get("Person");
+        assertEquals(((Schema) schema2.getProperties().get("array_property")).getNullable(), true);
+        assertEquals(((Schema) schema2.getProperties().get("set_property")).getNullable(), null);
+        assertEquals(((Schema) schema2.getProperties().get("map_property")).getNullable(), true);
+
+        // test `set`
+        OpenAPI openAPI2 = TestUtils.parseSpec("src/test/resources/3_0/setContainerToNullable_test.yaml");
+
+        Schema schema3 = openAPI2.getComponents().getSchemas().get("Person");
+        assertEquals(((Schema) schema3.getProperties().get("array_property")).getNullable(), null);
+        assertEquals(((Schema) schema3.getProperties().get("set_property")).getNullable(), null);
+        assertEquals(((Schema) schema3.getProperties().get("map_property")).getNullable(), null);
+
+        options.put("SET_CONTAINER_TO_NULLABLE", "set");
+        OpenAPINormalizer openAPINormalizer2 = new OpenAPINormalizer(openAPI2, options);
+        openAPINormalizer2.normalize();
+
+        Schema schema4 = openAPI2.getComponents().getSchemas().get("Person");
+        assertEquals(((Schema) schema4.getProperties().get("array_property")).getNullable(), null);
+        assertEquals(((Schema) schema4.getProperties().get("set_property")).getNullable(), true);
+        assertEquals(((Schema) schema4.getProperties().get("map_property")).getNullable(), null);
+    }
 }

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

@@ -0,0 +1,90 @@
+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:
+      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"
+    delete:
+      tags:
+        - person
+      x-internal: true
+      parameters:
+        - name: personId
+          in: path
+          required: true
+          description: The id of the person to retrieve
+          schema:
+            type: string
+      operationId: delete
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Person"
+    put:
+      tags:
+        - person
+      parameters:
+        - name: personId
+          in: path
+          required: true
+          description: The id of the person to retrieve
+          schema:
+            type: string
+      operationId: put
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Person"
+
+components:
+  schemas:
+    Person:
+      description: person
+      type: object
+      properties:
+        lastName:
+          type: string
+        firstName:
+          type: string
+        array_property:
+          type: array
+          items:
+            type: string
+        set_property:
+          type: array
+          uniqueItems: true
+          items:
+            type: string
+        map_property:
+          type: object
+          additionalProperties:
+            type: string