[java] Fix annotationLibrary option being ignored (#21992)

* Only register the Swagger annotation imports for the corresponding annotationLibrary

* Fix the issue in a specific generator

* Add unit test

Author: shybovycha

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

@@ -1088,6 +1088,10 @@ public CodegenModel fromModel(String name, Schema model) {
             }
         }
 
+        if (!AnnotationLibrary.SWAGGER2.equals(getAnnotationLibrary())) {
+            codegenModel.imports.remove("Schema");
+        }
+
         return codegenModel;
     }
 

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

@@ -3481,6 +3481,64 @@ public void callNativeServiceWithEmptyResponseSync() throws IOException {
         );
     }
 
+    @Test
+    public void annotationLibraryDoesNotCauseImportConflicts() throws IOException {
+        Map<String, Object> properties = new HashMap<>();
+        properties.put("annotationLibrary", "none");
+
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+            .setGeneratorName(JAVA_GENERATOR)
+            .setLibrary(JavaClientCodegen.NATIVE)
+            .setAdditionalProperties(properties)
+            .setInputSpec("src/test/resources/3_0/java/native/issue21991.yaml")
+            .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+
+        Map<String, File> files = generator.opts(clientOptInput).generate().stream()
+            .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        File apiFile = files.get("Schema.java");
+        assertNotNull(apiFile);
+
+        JavaFileAssert.assertThat(apiFile).fileDoesNotContain(
+            "import io.swagger.v3.oas.annotations.media.Schema;"
+        );
+    }
+
+    @Test
+    public void annotationLibraryGeneratesCorrectImports() throws IOException {
+        Map<String, Object> properties = new HashMap<>();
+        properties.put("annotationLibrary", "swagger2");
+
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+            .setGeneratorName(JAVA_GENERATOR)
+            .setLibrary(JavaClientCodegen.NATIVE)
+            .setAdditionalProperties(properties)
+            .setInputSpec("src/test/resources/3_0/java/native/issue21991.yaml")
+            .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+
+        Map<String, File> files = generator.opts(clientOptInput).generate().stream()
+            .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        File apiFile = files.get("Schema.java");
+        assertNotNull(apiFile);
+
+        JavaFileAssert.assertThat(apiFile).fileContains(
+            "import io.swagger.v3.oas.annotations.media.Schema;"
+        );
+    }
+
 
     /**
      * This checks that the async client is not affected by this fix.
@@ -3924,4 +3982,4 @@ public void oneOfWithInnerModelTest() {
         }
         assertTrue(speciesSeen);
     }
-}
+}

modules/openapi-generator/src/test/resources/3_0/java/native/issue21991.yaml

@@ -0,0 +1,29 @@
+openapi: 3.0.3
+info:
+  title: Example Hello API
+  description: ''
+  version: v1
+servers:
+  - url: http://localhost
+    description: Global Endpoint
+paths:
+  /v1/emptyResponse:
+    get:
+      operationId: empty
+      description: returns an empty response
+      responses:
+        200:
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Schema'
+        204:
+          description: Empty response
+components:
+  schemas:
+    Schema:
+      type: object
+      properties:
+        name:
+          type: string