[kotlin][jvm-retrofit2] Use @http with hasBody for DELETE operations with a request body (#25469)

Retrofit rejects @Body, @FormUrlEncoded and @multipart on @delete, so a
DELETE operation with a requestBody failed on its first call. Emit
@http(method, path, hasBody = true) only when the method does not allow a
body and the operation has body or form params. Other operations keep the
short annotation, so existing output does not change.

Fixes #25454

Author: cpruijsen

modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-retrofit2/api.mustache

@@ -155,7 +155,17 @@ import okhttp3.MultipartBody
     {{/-first}}
     {{/prioritizedContentTypes}}
     {{/formParams}}
+    {{^isBodyAllowed}}
+    {{#hasBodyOrFormParams}}
+    @HTTP(method = "{{httpMethod}}", path = "{{{path}}}", hasBody = true)
+    {{/hasBodyOrFormParams}}
+    {{^hasBodyOrFormParams}}
     @{{httpMethod}}("{{{path}}}")
+    {{/hasBodyOrFormParams}}
+    {{/isBodyAllowed}}
+    {{#isBodyAllowed}}
+    @{{httpMethod}}("{{{path}}}")
+    {{/isBodyAllowed}}
     {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}{{^doNotUseRxAndCoroutines}}{{#useCoroutines}}suspend {{/useCoroutines}}{{/doNotUseRxAndCoroutines}}fun {{operationId}}({{^allParams}}){{/allParams}}{{#allParams}}{{>queryParams}}{{>pathParams}}{{>headerParams}}{{>bodyParams}}{{>formParams}}{{^-last}}, {{/-last}}{{#-last}}){{/-last}}{{/allParams}}{{#returnType}}: {{/returnType}}{{^returnType}}{{#useResponseAsReturnType}}: {{/useResponseAsReturnType}}{{/returnType}}{{^doNotUseRxAndCoroutines}}{{#useRxJava}}Observable<{{#isResponseFile}}ResponseBody{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{^returnType}}Unit{{/returnType}}{{/isResponseFile}}>{{/useRxJava}}{{#useRxJava2}}{{#returnType}}Single<{{#isResponseFile}}ResponseBody{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}>{{/returnType}}{{^returnType}}Completable{{/returnType}}{{/useRxJava2}}{{#useRxJava3}}{{#returnType}}Single<{{#isResponseFile}}ResponseBody{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}>{{/returnType}}{{^returnType}}Completable{{/returnType}}{{/useRxJava3}}{{#useCoroutines}}{{#useResponseAsReturnType}}Response<{{/useResponseAsReturnType}}{{#isResponseFile}}ResponseBody{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{^returnType}}{{#useResponseAsReturnType}}Unit{{/useResponseAsReturnType}}{{/returnType}}{{/isResponseFile}}{{#useResponseAsReturnType}}>{{/useResponseAsReturnType}}{{/useCoroutines}}{{/doNotUseRxAndCoroutines}}{{#doNotUseRxAndCoroutines}}Call<{{#isResponseFile}}ResponseBody{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{^returnType}}Unit{{/returnType}}{{/isResponseFile}}>{{/doNotUseRxAndCoroutines}}
 
     {{/operation}}

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

@@ -103,6 +103,29 @@ public void testUseResponseAsReturnType(Object useResponseAsReturnType, String e
         assertFileContainsLine(lines, "suspend fun deletePet(@Path(\"petId\") petId: kotlin.Long, @Header(\"api_key\") apiKey: kotlin.String? = null)" + expectedUnitResponse);
     }
 
+    @Test
+    public void testRetrofit2DeleteWithBodyUsesHttpAnnotation_25454() throws IOException {
+        OpenAPI openAPI = readOpenAPI("src/test/resources/3_0/kotlin/issue25454-delete-with-body.yaml");
+
+        KotlinClientCodegen codegen = createCodegen(ClientLibrary.JVM_RETROFIT2);
+
+        ClientOptInput input = createClientOptInput(openAPI, codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        enableOnlyApiGeneration(generator);
+
+        List<File> files = generator.opts(input).generate();
+        File defaultApi = files.stream().filter(file -> file.getName().equals("DefaultApi.kt")).findAny().orElseThrow();
+        List<String> lines = Files.readAllLines(defaultApi.toPath()).stream().map(String::trim).collect(Collectors.toList());
+
+        // Retrofit rejects @Body, @FormUrlEncoded and @Multipart on @DELETE, so these need @HTTP with hasBody
+        assertFileContainsLine(lines, "@HTTP(method = \"DELETE\", path = \"items\", hasBody = true)");
+        assertFileContainsLine(lines, "@HTTP(method = \"DELETE\", path = \"items/form\", hasBody = true)");
+        // operations without a body, and methods that allow a body, keep the short annotation
+        assertFileContainsLine(lines, "@DELETE(\"items/{id}\")");
+        assertFileContainsLine(lines, "@POST(\"items\")");
+    }
+
     @Test
     public void testOptionalParamsHaveDefaultNullJvmKtor() throws IOException {
         OpenAPI openAPI = readOpenAPI("3_0/kotlin/petstore.yaml");

modules/openapi-generator/src/test/resources/3_0/kotlin/issue25454-delete-with-body.yaml

@@ -0,0 +1,64 @@
+openapi: 3.0.3
+info:
+  title: Repro
+  version: 1.0.0
+paths:
+  /items:
+    delete:
+      operationId: deleteItems
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/DeleteItemsRequest"
+      responses:
+        "204":
+          description: Deleted
+    post:
+      operationId: createItems
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/DeleteItemsRequest"
+      responses:
+        "204":
+          description: Created
+  /items/form:
+    delete:
+      operationId: deleteItemsForm
+      requestBody:
+        content:
+          application/x-www-form-urlencoded:
+            schema:
+              type: object
+              properties:
+                id:
+                  type: string
+      responses:
+        "204":
+          description: Deleted
+  /items/{id}:
+    delete:
+      operationId: deleteItem
+      parameters:
+        - name: id
+          in: path
+          required: true
+          schema:
+            type: string
+      responses:
+        "204":
+          description: Deleted
+components:
+  schemas:
+    DeleteItemsRequest:
+      type: object
+      required: [ids]
+      properties:
+        ids:
+          type: array
+          items:
+            type: string