feat: [JAVA] [webclient] [#16589] Support file abstraction for WebClient responses (#16590)

* Support file abstraction for  WebClient responses

Issue-16589

* Fix issue flagged by tests. Yay tests!

Issue-16589

* Update generation of test file too

* Fix generated tests for webclient, resttemplate

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/api_test.mustache

@@ -36,7 +36,8 @@ public class {{classname}}Test {
         {{#allParams}}
         {{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.Resource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.Resource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}} = null;
         {{/allParams}}
-        {{#returnType}}{{{.}}} response = {{/returnType}}api.{{operationId}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});
+
+        {{#returnType}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{.}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{.}}}{{/isResponseFile}} response = {{/returnType}}api.{{operationId}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});
 
         // TODO: test validations
     }

modules/openapi-generator/src/main/resources/Java/libraries/webclient/api.mustache

@@ -129,7 +129,7 @@ public class {{classname}} {
 
         String[] localVarAuthNames = new String[] { {{#authMethods}}"{{name}}"{{^-last}}, {{/-last}}{{/authMethods}} };
 
-        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
+        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
         return apiClient.invokeAPI("{{{path}}}", HttpMethod.{{httpMethod}}, pathParams, queryParams, postBody, headerParams, cookieParams, formParams, localVarAccept, localVarContentType, localVarAuthNames, localVarReturnType);
     }
 
@@ -145,8 +145,8 @@ public class {{classname}} {
     * @see <a href="{{url}}">{{summary}} Documentation</a>
 {{/externalDocs}}
      */
-    public {{#returnType}}{{#vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#uniqueItems}}Set{{/uniqueItems}}{{^uniqueItems}}List{{/uniqueItems}}<{{{returnBaseType}}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}Flux<{{{returnBaseType}}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}Mono<{{{returnType}}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}} {{/returnType}}{{^returnType}}{{#vendorExtensions.x-webclient-blocking}}void{{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}Mono<Void>{{/vendorExtensions.x-webclient-blocking}} {{/returnType}}{{operationId}}({{#allParams}}{{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.AbstractResource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.AbstractResource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws WebClientResponseException {
+    public {{#returnType}}{{#vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#uniqueItems}}Set{{/uniqueItems}}{{^uniqueItems}}List{{/uniqueItems}}<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}Flux<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}Mono<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}} {{/returnType}}{{^returnType}}{{#vendorExtensions.x-webclient-blocking}}void{{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}Mono<Void>{{/vendorExtensions.x-webclient-blocking}} {{/returnType}}{{operationId}}({{#allParams}}{{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.AbstractResource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.AbstractResource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws WebClientResponseException {
-        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
+        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
         {{^returnType}}{{^vendorExtensions.x-webclient-blocking}}return {{/vendorExtensions.x-webclient-blocking}}{{/returnType}}{{#returnType}}return {{/returnType}}{{operationId}}RequestCreation({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}).{{#vendorExtensions.x-webclient-return-except-list-of-string}}bodyToFlux{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}bodyToMono{{/vendorExtensions.x-webclient-return-except-list-of-string}}(localVarReturnType){{#vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#uniqueItems}}.collect(Collectors.toSet()){{/uniqueItems}}{{^uniqueItems}}.collectList(){{/uniqueItems}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}.block(){{/vendorExtensions.x-webclient-blocking}};
     }
 
@@ -162,8 +162,8 @@ public class {{classname}} {
      * @see <a href="{{url}}">{{summary}} Documentation</a>
 {{/externalDocs}}
      */
-    public {{#vendorExtensions.x-webclient-blocking}}{{#returnType}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}ResponseEntity<List<{{{returnBaseType}}}>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}ResponseEntity<{{{returnType}}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/returnType}}{{^returnType}}ResponseEntity<Void>{{/returnType}} {{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}{{#returnType}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}Mono<ResponseEntity<List<{{{returnBaseType}}}>>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}Mono<ResponseEntity<{{{returnType}}}>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/returnType}}{{^returnType}}Mono<ResponseEntity<Void>>{{/returnType}} {{/vendorExtensions.x-webclient-blocking}}{{operationId}}WithHttpInfo({{#allParams}}{{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.AbstractResource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.AbstractResource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws WebClientResponseException {
+    public {{#vendorExtensions.x-webclient-blocking}}{{#returnType}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}ResponseEntity<List<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}ResponseEntity<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/returnType}}{{^returnType}}ResponseEntity<Void>{{/returnType}} {{/vendorExtensions.x-webclient-blocking}}{{^vendorExtensions.x-webclient-blocking}}{{#returnType}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}Mono<ResponseEntity<List<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}>>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}Mono<ResponseEntity<{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}>>{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/returnType}}{{^returnType}}Mono<ResponseEntity<Void>>{{/returnType}} {{/vendorExtensions.x-webclient-blocking}}{{operationId}}WithHttpInfo({{#allParams}}{{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.AbstractResource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.AbstractResource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws WebClientResponseException {
-        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnBaseType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{{returnType}}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
+        {{#returnType}}ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}> localVarReturnType = new ParameterizedTypeReference<{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnBaseType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnBaseType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{returnType}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{returnType}}}{{/isResponseFile}}{{/vendorExtensions.x-webclient-return-except-list-of-string}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localVarReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
         return {{operationId}}RequestCreation({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}).{{#vendorExtensions.x-webclient-return-except-list-of-string}}toEntityList{{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}toEntity{{/vendorExtensions.x-webclient-return-except-list-of-string}}(localVarReturnType){{#vendorExtensions.x-webclient-blocking}}.block(){{/vendorExtensions.x-webclient-blocking}};
     }
 

modules/openapi-generator/src/main/resources/Java/libraries/webclient/api_test.mustache

@@ -32,7 +32,7 @@ public class {{classname}}Test {
         {{#allParams}}
         {{#isFile}}{{#useAbstractionForFiles}}{{#collectionFormat}}java.util.Collection<org.springframework.core.io.AbstractResource>{{/collectionFormat}}{{^collectionFormat}}org.springframework.core.io.AbstractResource{{/collectionFormat}}{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{dataType}}}{{/useAbstractionForFiles}}{{/isFile}}{{^isFile}}{{{dataType}}}{{/isFile}} {{paramName}} = null;
         {{/allParams}}
-        {{#returnType}}{{{.}}} response = {{/returnType}}api.{{operationId}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}){{^vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#uniqueItems}}.collect(Collectors.toSet()){{/uniqueItems}}{{^uniqueItems}}.collectList(){{/uniqueItems}}.block(){{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}.block(){{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}};
+        {{#returnType}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{.}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{.}}}{{/isResponseFile}} response = {{/returnType}}api.{{operationId}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}){{^vendorExtensions.x-webclient-blocking}}{{#vendorExtensions.x-webclient-return-except-list-of-string}}{{#uniqueItems}}.collect(Collectors.toSet()){{/uniqueItems}}{{^uniqueItems}}.collectList(){{/uniqueItems}}.block(){{/vendorExtensions.x-webclient-return-except-list-of-string}}{{^vendorExtensions.x-webclient-return-except-list-of-string}}.block(){{/vendorExtensions.x-webclient-return-except-list-of-string}}{{/vendorExtensions.x-webclient-blocking}};
 
         // TODO: test validations
     }

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

@@ -2647,6 +2647,37 @@ public class JavaClientCodegenTest {
     }
 
     @Test
+    public void testWebClientResponseTypeWithUseAbstractionForFiles_issue16589() throws IOException {
+        Map<String, Object> properties = new HashMap<>();
+        properties.put(CodegenConstants.API_PACKAGE, "xyz.abcdef.api");
+        properties.put(JavaClientCodegen.USE_ABSTRACTION_FOR_FILES, true);
+
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+            .setGeneratorName("java")
+            .setLibrary(JavaClientCodegen.WEBCLIENT)
+            .setAdditionalProperties(properties)
+            .setInputSpec("src/test/resources/3_0/issue13146_file_abstraction_response.yaml")
+            .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(configurator.toClientOptInput()).generate();
+        files.forEach(File::deleteOnExit);
+
+        validateJavaSourceFiles(files);
+
+        Path defaultApi = Paths.get(output + "/src/main/java/xyz/abcdef/api/ResourceApi.java");
+
+        TestUtils.assertFileContains(defaultApi,
+            "Mono<org.springframework.core.io.Resource> resourceInResponse()",
+            "Mono<ResponseEntity<org.springframework.core.io.Resource>> resourceInResponseWithHttpInfo()",
+            "ParameterizedTypeReference<org.springframework.core.io.Resource> localVarReturnType = new ParameterizedTypeReference<org.springframework.core.io.Resource>()"
+        );
+    }
+
     public void testHandleConstantParams() throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
         output.deleteOnExit();
@@ -2672,5 +2703,4 @@ public class JavaClientCodegenTest {
                         .bodyContainsLines(
                                         "localVarHeaderParams.put(\"X-CUSTOM_CONSTANT_HEADER\", \"CONSTANT_VALUE\")");
     }
-
 }