Process additionalProperties: true as arbitrary type instead of object

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

@@ -1203,12 +1203,11 @@ public static Schema getAdditionalProperties(OpenAPI openAPI, Schema schema) {
             */
         }
         if (addProps == null || (addProps instanceof Boolean && (Boolean) addProps)) {
-            // Return ObjectSchema to specify any object (map) value is allowed.
-            // Set nullable to specify the value of additional properties may be
-            // the null value.
-            // Free-form additionalProperties don't need to have an inner
-            // additional properties, the type is already free-form.
-            return new ObjectSchema().additionalProperties(Boolean.FALSE).nullable(Boolean.TRUE);
+            // Return an empty schema as the properties can take on any type per
+            // the spec. See
+            // https://github.com/OpenAPITools/openapi-generator/issues/9282 for
+            // more details.
+            return new Schema();
         }
         return null;
     }

modules/openapi-generator/src/main/resources/typescript-axios/modelGeneric.mustache

@@ -5,7 +5,7 @@
  */
 export interface {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{
 {{#additionalPropertiesType}}
-    [key: string]: {{{additionalPropertiesType}}}{{#hasVars}} | any{{/hasVars}};
+    [key: string]: {{{additionalPropertiesType}}}{{^additionalPropertiesIsAnyType}}{{#hasVars}} | any{{/hasVars}}{{/additionalPropertiesIsAnyType}};
 
 {{/additionalPropertiesType}}
 {{#vars}}

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

@@ -447,7 +447,7 @@ public void testAdditionalPropertiesV3SpecDisallowAdditionalPropertiesIfNotPrese
         // extended with any undeclared properties.
         Schema addProps = ModelUtils.getAdditionalProperties(openAPI, componentSchema);
         Assert.assertNotNull(addProps);
-        Assert.assertTrue(addProps instanceof ObjectSchema);
+        Assert.assertEquals(addProps, new Schema());
         CodegenModel cm = codegen.fromModel("AdditionalPropertiesClass", componentSchema);
         Assert.assertNotNull(cm.getAdditionalProperties());
 
@@ -492,7 +492,7 @@ public void testAdditionalPropertiesV3SpecDisallowAdditionalPropertiesIfNotPrese
         Assert.assertNull(map_with_undeclared_properties_anytype_1_sc.getAdditionalProperties());
         addProps = ModelUtils.getAdditionalProperties(openAPI, map_with_undeclared_properties_anytype_1_sc);
         Assert.assertNotNull(addProps);
-        Assert.assertTrue(addProps instanceof ObjectSchema);
+        Assert.assertEquals(addProps, new Schema());
         Assert.assertNotNull(map_with_undeclared_properties_anytype_1_cp.getAdditionalProperties());
 
         // map_with_undeclared_properties_anytype_2
@@ -502,7 +502,7 @@ public void testAdditionalPropertiesV3SpecDisallowAdditionalPropertiesIfNotPrese
         Assert.assertNull(map_with_undeclared_properties_anytype_2_sc.getAdditionalProperties());
         addProps = ModelUtils.getAdditionalProperties(openAPI, map_with_undeclared_properties_anytype_2_sc);
         Assert.assertNotNull(addProps);
-        Assert.assertTrue(addProps instanceof ObjectSchema);
+        Assert.assertEquals(addProps, new Schema());
         Assert.assertNotNull(map_with_undeclared_properties_anytype_2_cp.getAdditionalProperties());
 
         // map_with_undeclared_properties_anytype_3
@@ -515,7 +515,7 @@ public void testAdditionalPropertiesV3SpecDisallowAdditionalPropertiesIfNotPrese
         Assert.assertEquals(map_with_undeclared_properties_anytype_3_sc.getAdditionalProperties(), Boolean.TRUE);
         addProps = ModelUtils.getAdditionalProperties(openAPI, map_with_undeclared_properties_anytype_3_sc);
         Assert.assertNotNull(addProps);
-        Assert.assertTrue(addProps instanceof ObjectSchema);
+        Assert.assertEquals(addProps, new Schema());
         Assert.assertNotNull(map_with_undeclared_properties_anytype_3_cp.getAdditionalProperties());
 
         // empty_map
@@ -2770,6 +2770,26 @@ public void testAdditionalPropertiesPresentInResponses() {
         }
     }
 
+    @Test
+    public void testAdditionalPropertiesAnyType() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/issue_9282.yaml");
+        final DefaultCodegen codegen = new DefaultCodegen();
+        codegen.setOpenAPI(openAPI);
+
+        CodegenProperty anyTypeSchema = codegen.fromProperty("", new Schema());
+
+        Schema sc;
+        CodegenModel cm;
+
+        sc = openAPI.getComponents().getSchemas().get("AdditionalPropertiesTrue");
+        cm = codegen.fromModel("AdditionalPropertiesTrue", sc);
+        assertEquals(cm.getVars().get(0).additionalProperties, anyTypeSchema);
+
+        sc = openAPI.getComponents().getSchemas().get("AdditionalPropertiesAnyType");
+        cm = codegen.fromModel("AdditionalPropertiesAnyType", sc);
+        assertEquals(cm.getVars().get(0).additionalProperties, anyTypeSchema);
+    }
+
     @Test
     public void testIsXPresence() {
         final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/issue_7651.yaml");

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

@@ -22,6 +22,7 @@
 import io.swagger.v3.oas.models.media.ArraySchema;
 import io.swagger.v3.oas.models.media.IntegerSchema;
 import io.swagger.v3.oas.models.media.MapSchema;
+import io.swagger.v3.oas.models.media.ObjectSchema;
 import io.swagger.v3.oas.models.media.Schema;
 import org.openapitools.codegen.CodegenConstants;
 import org.openapitools.codegen.CodegenType;
@@ -90,6 +91,13 @@ public void getTypeDeclarationTest() {
         ModelUtils.setGenerateAliasAsModel(true);
         defaultValue = codegen.getTypeDeclaration(schema);
         Assert.assertEquals(defaultValue, "map[string]NestedArray");
+
+        // Create object schema with additionalProperties set to true
+        schema = new ObjectSchema().additionalProperties(Boolean.TRUE);
+
+        ModelUtils.setGenerateAliasAsModel(false);
+        defaultValue = codegen.getTypeDeclaration(schema);
+        Assert.assertEquals(defaultValue, "map[string]interface{}");
     }
 
     private static class P_AbstractGoCodegen extends AbstractGoCodegen {

modules/openapi-generator/src/test/resources/3_0/issue_9282.yaml

@@ -0,0 +1,18 @@
+openapi: 3.0.0
+components:
+  schemas:
+    AdditionalPropertiesTrue:
+      description: additionalProperties set to true
+      type: object
+      properties:
+        child:
+          type: object
+          additionalProperties: true
+
+    AdditionalPropertiesAnyType:
+      description: additionalProperties set to any type explicitly
+      type: object
+      properties:
+        child:
+          type: object
+          additionalProperties: {}

samples/client/petstore/typescript-axios/builds/test-petstore/api.ts

@@ -59,10 +59,10 @@ export interface AdditionalPropertiesClass {
     'map_with_undeclared_properties_anytype_2'?: object;
     /**
      * 
-     * @type {{ [key: string]: object; }}
+     * @type {{ [key: string]: any; }}
      * @memberof AdditionalPropertiesClass
      */
-    'map_with_undeclared_properties_anytype_3'?: { [key: string]: object; };
+    'map_with_undeclared_properties_anytype_3'?: { [key: string]: any; };
     /**
      * an object with no declared properties and no undeclared properties, hence it\'s an empty map.
      * @type {object}
@@ -1706,7 +1706,7 @@ export interface Whale {
  * @interface Zebra
  */
 export interface Zebra {
-    [key: string]: object | any;
+    [key: string]: any;
 
     /**
      * 

samples/client/petstore/typescript-axios/builds/with-fake-endpoints-models-for-testing-with-http-signature/api.ts

@@ -173,7 +173,7 @@ export interface ArrayTest {
  * @interface Banana
  */
 export interface Banana {
-    [key: string]: object | any;
+    [key: string]: any;
 
     /**
      *