Extension detected by customization flag

codegen/src/main/java/software/amazon/awssdk/codegen/model/config/customization/CustomizationConfig.java

@@ -196,6 +196,10 @@ public class CustomizationConfig {
 
     private RetryMode defaultRetryMode;
 
+    /**
+     * The name of the interface that the client interface should extend.
+     */
+    private String extensionInterface;
 
 
     private CustomizationConfig() {
@@ -502,4 +506,12 @@ public ServiceConfig getServiceConfig() {
     public void setServiceConfig(ServiceConfig serviceConfig) {
         this.serviceConfig = serviceConfig;
     }
+
+    public String getExtensionInterface() {
+        return extensionInterface;
+    }
+
+    public void setExtensionInterface(String extensionInterface) {
+        this.extensionInterface = extensionInterface;
+    }
 }

codegen/src/main/java/software/amazon/awssdk/codegen/poet/PoetUtils.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.codegen.poet;
 
+import static software.amazon.awssdk.utils.StringUtils.isEmpty;
 import static software.amazon.awssdk.utils.StringUtils.isNotBlank;
 
 import com.squareup.javapoet.AnnotationSpec;
@@ -29,13 +30,17 @@
 import java.util.Optional;
 import java.util.function.Consumer;
 import javax.lang.model.element.Modifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import software.amazon.awssdk.annotations.Generated;
+import software.amazon.awssdk.codegen.model.config.customization.CustomizationConfig;
 import software.amazon.awssdk.codegen.model.intermediate.DocumentationModel;
 import software.amazon.awssdk.codegen.model.intermediate.HasDeprecation;
-import software.amazon.awssdk.core.internal.util.ClassLoaderHelper;
 
 public final class PoetUtils {
 
+    private static final Logger log = LoggerFactory.getLogger(PoetUtils.class);
+
     private static final AnnotationSpec GENERATED = AnnotationSpec.builder(Generated.class)
                                                                   .addMember("value", "$S", "software.amazon.awssdk:codegen")
                                                                   .build();
@@ -112,18 +117,21 @@ public static JavaFile buildJavaFile(ClassSpec spec) {
         return builder.build();
     }
 
-    public static Optional<Class<?>> findExtensionInterface(ClassName clientInterfaceName, Class<?> classLoaderClass) {
-        String extensionClassName = String.format("%sExtensionMethods", clientInterfaceName.canonicalName());
-        try {
-            Class<?> extensionClass = ClassLoaderHelper.loadClass(extensionClassName, classLoaderClass);
-            if (extensionClass.isInterface()) {
-                return Optional.of(extensionClass);
+    public static Optional<ClassName> findExtensionInterface(ClassName clientInterfaceName,
+                                                             CustomizationConfig customizationConfig) {
+        String extensionInterfaceFqcn = customizationConfig.getExtensionInterface();
+
+        if (!isEmpty(extensionInterfaceFqcn)) {
+            ClassName interfaceName = classNameFromFqcn(extensionInterfaceFqcn);
+            log.info(String.format("Found client extension interface %s.", interfaceName));
+            if (!interfaceName.packageName().contains(clientInterfaceName.packageName())) {
+                throw new IllegalArgumentException(
+                    String.format("Extension interface package is not part of service client package. "
+                                  + "Client package: %s. Extension interface package: %s",
+                                  clientInterfaceName.packageName(), interfaceName.packageName()));
             }
-            throw new IllegalStateException("Loaded class, but it is not an interface: " + extensionClassName + ".");
-        } catch (ClassNotFoundException e) {
-            return Optional.empty();
-        } catch (NoClassDefFoundError e) {
-            throw new IllegalStateException("Failed to load extension " + extensionClassName + ".", e);
+            return Optional.of(interfaceName);
         }
+        return Optional.empty();
     }
 }

codegen/src/main/java/software/amazon/awssdk/codegen/poet/client/SyncClientInterface.java

@@ -94,7 +94,7 @@ public TypeSpec poetSpec() {
                                               ServiceMetadataProvider.class)
                                   .build());
 
-        Optional<Class<?>> extensionClass = PoetUtils.findExtensionInterface(className, getClass());
+        Optional<ClassName> extensionClass = PoetUtils.findExtensionInterface(className, model.getCustomizationConfig());
         extensionClass.ifPresent(result::addSuperinterface);
 
         PoetUtils.addJavadoc(result::addJavadoc, getJavadoc());

codegen/src/test/java/software/amazon/awssdk/codegen/poet/utils/PoetUtilsTest.java

@@ -21,6 +21,7 @@
 import com.squareup.javapoet.ClassName;
 import java.util.Optional;
 import org.junit.jupiter.api.Test;
+import software.amazon.awssdk.codegen.model.config.customization.CustomizationConfig;
 import software.amazon.awssdk.codegen.poet.PoetUtils;
 import software.amazon.awssdk.codegen.poet.client.SyncClientInterface;
 
@@ -31,24 +32,29 @@ public class PoetUtilsTest {
 
     @Test
     public void findExtensionInterface_whenNotExists_returnEmpty() {
-        ClassName cl = ClassName.get("software.amazon.awssdk.codegen.poet.utils", "NoClient");
-        Optional<Class<?>> extensionClass = PoetUtils.findExtensionInterface(cl, SyncClientInterface.class);
+        ClassName cl = ClassName.get("software.amazon.awssdk.sdkservice", "SdkServiceClient");
+        CustomizationConfig customizationConfig = CustomizationConfig.create();
+        Optional<ClassName> extensionClass = PoetUtils.findExtensionInterface(cl, customizationConfig);
         assertThat(extensionClass).isEmpty();
     }
 
     @Test
     public void findExtensionInterface_whenExists_returnClass() {
-        ClassName cl = ClassName.get("software.amazon.awssdk.codegen.poet.utils","CorrectClient");
-        Optional<Class<?>> extensionClass = PoetUtils.findExtensionInterface(cl, getClass());
+        ClassName cl = ClassName.get("software.amazon.awssdk.sdkservice","SdkServiceClient");
+        CustomizationConfig customizationConfig = CustomizationConfig.create();
+        customizationConfig.setExtensionInterface("software.amazon.awssdk.sdkservice.SdkServiceClientExtensionMethods");
+        Optional<ClassName> extensionClass = PoetUtils.findExtensionInterface(cl, customizationConfig);
         assertThat(extensionClass).isPresent();
-        assertThat(extensionClass.get().getSimpleName()).isEqualTo("CorrectClientExtensionMethods");
+        assertThat(extensionClass.get().canonicalName()).isEqualTo("software.amazon.awssdk.sdkservice.SdkServiceClientExtensionMethods");
     }
 
     @Test
-    public void findExtensionInterface_whenIncorrectType_throwException() {
-        ClassName cl = ClassName.get("software.amazon.awssdk.codegen.poet.utils","IncorrectClient");
-        assertThatThrownBy(() -> PoetUtils.findExtensionInterface(cl, getClass()))
-            .isInstanceOf(IllegalStateException.class)
-            .hasMessageContaining("interface");
+    public void findExtensionInterface_differentPackages_throwsException() {
+        ClassName cl = ClassName.get("software.amazon.awssdk.sdkservice","SdkServiceClient");
+        CustomizationConfig customizationConfig = CustomizationConfig.create();
+        customizationConfig.setExtensionInterface("software.amazon.awssdk.someotherpackage.SdkServiceClientExtensionMethods");
+        assertThatThrownBy(() -> PoetUtils.findExtensionInterface(cl, customizationConfig))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessageContaining("package");
     }
 }

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/client/c2j/clientextensions/customization.config

@@ -1,3 +1,3 @@
 {
-  "customServiceMetadata": {"contentType" : "application/json"}
+  "extensionInterface": "software.amazon.awssdk.services.sdkextensions.extensions.SdkExtensionsClientExtensionMethods"
 }

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/client/test-clientextensions-sync-interface.java

@@ -8,6 +8,7 @@
 import software.amazon.awssdk.core.SdkClient;
 import software.amazon.awssdk.core.exception.SdkClientException;
 import software.amazon.awssdk.regions.ServiceMetadata;
+import software.amazon.awssdk.services.sdkextensions.extensions.SdkExtensionsClientExtensionMethods;
 import software.amazon.awssdk.services.sdkextensions.model.OneOperationRequest;
 import software.amazon.awssdk.services.sdkextensions.model.OneOperationResponse;
 import software.amazon.awssdk.services.sdkextensions.model.SdkExtensionsException;

services/s3/src/it/java/software/amazon/awssdk/services/s3/extensions/BucketExistsIntegrationTest.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.awssdk.services.s3.extensions;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static software.amazon.awssdk.testutils.service.S3BucketUtils.temporaryBucketName;
+
+import java.io.IOException;
+import java.util.Random;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import software.amazon.awssdk.services.s3.S3IntegrationTestBase;
+
+public class BucketExistsIntegrationTest extends S3IntegrationTestBase {
+
+    private static final String BUCKET = temporaryBucketName(BucketExistsIntegrationTest.class);
+
+    @BeforeClass
+    public static void setupFixture() throws IOException {
+        createBucket(BUCKET);
+    }
+
+    @AfterClass
+    public static void tearDownFixture() {
+        deleteBucketAndAllContents(BUCKET);
+    }
+
+    @Test
+    public void bucketExists() {
+        assertThat(s3.doesBucketExist(BUCKET)).isTrue();
+    }
+
+    @Test
+    public void bucketDoesNotExist() {
+        assertThat(s3.doesBucketExist(temporaryBucketName("noexist"))).isFalse();
+    }
+}

services/s3/src/main/resources/codegen-resources/customization.config

@@ -159,5 +159,6 @@
     "createMethodParams": [
       "clientConfiguration"
     ]
-  }
+  },
+  "extensionInterface": "software.amazon.awssdk.services.s3.extensions.S3ClientExtensionMethods"
 }