Minor refactoring on auth scheme provider: rename ModeledAuthSchemePr…

codegen/src/main/java/software/amazon/awssdk/codegen/poet/auth/scheme/AuthSchemeSpecUtils.java

@@ -87,8 +87,8 @@ public ClassName defaultAuthSchemeProviderName() {
         return ClassName.get(internalPackage(), "Default" + providerInterfaceName().simpleName());
     }
 
-    public ClassName modeledAuthSchemeProviderName() {
-        return ClassName.get(internalPackage(), "Modeled" + providerInterfaceName().simpleName());
+    public ClassName fallbackAuthSchemeProviderName() {
+        return ClassName.get(internalPackage(), "Fallback" + providerInterfaceName().simpleName());
     }
 
     public ClassName preferredAuthSchemeProviderName() {

codegen/src/main/java/software/amazon/awssdk/codegen/poet/auth/scheme/EndpointBasedAuthSchemeProviderSpec.java

@@ -49,6 +49,20 @@
 import software.amazon.awssdk.utils.CompletableFutureUtils;
 import software.amazon.awssdk.utils.Validate;
 
+/**
+ * Generates an auth scheme provider that resolves authentication schemes from endpoint rules.
+ * <p>
+ * This class creates a provider that determines authentication schemes dynamically based on the resolved endpoint's auth scheme
+ * attributes. It first resolves the endpoint using endpoint rules, then extracts auth scheme information from the endpoint's
+ * attributes. If the endpoint doesn't specify auth schemes (for example, a custom endpoint provider is used), it delegates to the
+ * fallback provider, which returns the default auth schemes defined in {@link AuthTypeToSigV4Default}
+ * <p>
+ * The generated provider handles AWS signature versions (SigV4, SigV4a) and service-specific schemes (like S3 Express),
+ * translating endpoint auth scheme metadata into {@link AuthSchemeOption} instances with appropriate signer properties.
+ * <p>
+ * This provider is only generated for services with endpoint-based auth enabled
+ * ({@code isEnableEndpointAuthSchemeParams() = true}).
+ */
 public class EndpointBasedAuthSchemeProviderSpec implements ClassSpec {
     private final AuthSchemeSpecUtils authSchemeSpecUtils;
     private final EndpointRulesSpecUtils endpointRulesSpecUtils;
@@ -124,9 +138,9 @@ private MethodSpec endpointProvider() {
     }
 
     private FieldSpec modeledResolverInstance() {
-        return FieldSpec.builder(authSchemeSpecUtils.providerInterfaceName(), "MODELED_RESOLVER")
+        return FieldSpec.builder(authSchemeSpecUtils.providerInterfaceName(), "FALLBACK_RESOLVER")
                         .addModifiers(Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL)
-                        .initializer("$T.create()", authSchemeSpecUtils.modeledAuthSchemeProviderName())
+                        .initializer("$T.create()", authSchemeSpecUtils.fallbackAuthSchemeProviderName())
                         .build();
     }
 
@@ -159,7 +173,7 @@ private MethodSpec resolveAuthSchemeMethod() {
         spec.addStatement("$T authSchemes = endpoint.attribute($T.AUTH_SCHEMES)",
                           ParameterizedTypeName.get(List.class, EndpointAuthScheme.class), AwsEndpointAttribute.class);
         spec.beginControlFlow("if (authSchemes == null)");
-        spec.addStatement("return MODELED_RESOLVER.resolveAuthScheme(params)");
+        spec.addStatement("return FALLBACK_RESOLVER.resolveAuthScheme(params)");
         spec.endControlFlow();
 
 

codegen/src/main/java/software/amazon/awssdk/codegen/poet/auth/scheme/ModelBasedAuthSchemeProviderSpec.java

@@ -31,6 +31,28 @@
 import software.amazon.awssdk.codegen.poet.PoetUtils;
 import software.amazon.awssdk.http.auth.spi.scheme.AuthSchemeOption;
 
+/**
+ * Generates an auth scheme provider implementation based on the service model's authentication configuration.
+ * <p>
+ * This class creates a provider that resolves authentication schemes for SDK operations. It supports both
+ * service-level default auth schemes and per-operation auth scheme overrides. When operations have different
+ * auth requirements, it generates a switch statement to return the appropriate schemes based on the operation name.
+ * <p>
+ * The generated provider implements the auth scheme provider interface and returns an ordered list of
+ * {@link AuthSchemeOption} instances that the SDK will attempt in sequence during authentication.
+ * <p>
+ * <b>Usage Scenarios:</b>
+ * <ul>
+ * <li><b>Services without endpoint-based auth:</b> The generated class serves as the default auth scheme provider,
+ * directly implementing all auth scheme resolution logic based on the service model.</li>
+ *
+ * <li><b>Services with endpoint-based auth</b>(enabled through enableEndpointAuthSchemeParams customization config): The
+ * generated class is named with a "Fallback" prefix and works
+ * alongside the endpoint-based provider. It acts as a fallback when endpoint rules don't specify auth schemes, which could
+ * happen if the endpoint provider is overridden by users. The auth schemes are derived from hardcoded
+ * {@link AuthTypeToSigV4Default}</li>
+ * </ul>
+ */
 public class ModelBasedAuthSchemeProviderSpec implements ClassSpec {
     private final AuthSchemeSpecUtils authSchemeSpecUtils;
     private final AuthSchemeCodegenKnowledgeIndex knowledgeIndex;
@@ -43,7 +65,7 @@ public ModelBasedAuthSchemeProviderSpec(IntermediateModel intermediateModel) {
     @Override
     public ClassName className() {
         if (authSchemeSpecUtils.useEndpointBasedAuthProvider()) {
-            return authSchemeSpecUtils.modeledAuthSchemeProviderName();
+            return authSchemeSpecUtils.fallbackAuthSchemeProviderName();
         }
         return authSchemeSpecUtils.defaultAuthSchemeProviderName();
     }

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/auth/scheme/query-endpoint-auth-params-auth-scheme-endpoint-provider-without-allowlist.java

@@ -30,7 +30,7 @@
 public final class DefaultQueryAuthSchemeProvider implements QueryAuthSchemeProvider {
     private static final DefaultQueryAuthSchemeProvider DEFAULT = new DefaultQueryAuthSchemeProvider();
 
-    private static final QueryAuthSchemeProvider MODELED_RESOLVER = ModeledQueryAuthSchemeProvider.create();
+    private static final QueryAuthSchemeProvider FALLBACK_RESOLVER = FallbackQueryAuthSchemeProvider.create();
 
     private static final QueryEndpointProvider DELEGATE = QueryEndpointProvider.defaultProvider();
 
@@ -54,7 +54,7 @@ public List<AuthSchemeOption> resolveAuthScheme(QueryAuthSchemeParams params) {
         Endpoint endpoint = CompletableFutureUtils.joinLikeSync(endpointProvider(params).resolveEndpoint(endpointParameters));
         List<EndpointAuthScheme> authSchemes = endpoint.attribute(AwsEndpointAttribute.AUTH_SCHEMES);
         if (authSchemes == null) {
-            return MODELED_RESOLVER.resolveAuthScheme(params);
+            return FALLBACK_RESOLVER.resolveAuthScheme(params);
         }
         List<AuthSchemeOption> options = new ArrayList<>();
         for (EndpointAuthScheme authScheme : authSchemes) {

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/auth/scheme/query-endpoint-auth-params-auth-scheme-endpoint-provider.java

@@ -30,7 +30,7 @@
 public final class DefaultQueryAuthSchemeProvider implements QueryAuthSchemeProvider {
     private static final DefaultQueryAuthSchemeProvider DEFAULT = new DefaultQueryAuthSchemeProvider();
 
-    private static final QueryAuthSchemeProvider MODELED_RESOLVER = ModeledQueryAuthSchemeProvider.create();
+    private static final QueryAuthSchemeProvider FALLBACK_RESOLVER = FallbackQueryAuthSchemeProvider.create();
 
     private static final QueryEndpointProvider DELEGATE = QueryEndpointProvider.defaultProvider();
 
@@ -50,7 +50,7 @@ public List<AuthSchemeOption> resolveAuthScheme(QueryAuthSchemeParams params) {
         Endpoint endpoint = CompletableFutureUtils.joinLikeSync(endpointProvider(params).resolveEndpoint(endpointParameters));
         List<EndpointAuthScheme> authSchemes = endpoint.attribute(AwsEndpointAttribute.AUTH_SCHEMES);
         if (authSchemes == null) {
-            return MODELED_RESOLVER.resolveAuthScheme(params);
+            return FALLBACK_RESOLVER.resolveAuthScheme(params);
         }
         List<AuthSchemeOption> options = new ArrayList<>();
         for (EndpointAuthScheme authScheme : authSchemes) {

codegen/src/test/resources/software/amazon/awssdk/codegen/poet/auth/scheme/query-endpoint-auth-params-auth-scheme-modeled-provider.java

@@ -12,7 +12,6 @@
  * express or implied. See the License for the specific language governing
  * permissions and limitations under the License.
  */
-
 package software.amazon.awssdk.services.query.auth.scheme.internal;
 
 import java.util.ArrayList;
@@ -27,31 +26,31 @@
 
 @Generated("software.amazon.awssdk:codegen")
 @SdkInternalApi
-public final class ModeledQueryAuthSchemeProvider implements QueryAuthSchemeProvider {
-    private static final ModeledQueryAuthSchemeProvider DEFAULT = new ModeledQueryAuthSchemeProvider();
+public final class FallbackQueryAuthSchemeProvider implements QueryAuthSchemeProvider {
+    private static final FallbackQueryAuthSchemeProvider DEFAULT = new FallbackQueryAuthSchemeProvider();
 
-    private ModeledQueryAuthSchemeProvider() {
+    private FallbackQueryAuthSchemeProvider() {
     }
 
-    public static ModeledQueryAuthSchemeProvider create() {
+    public static FallbackQueryAuthSchemeProvider create() {
         return DEFAULT;
     }
 
     @Override
     public List<AuthSchemeOption> resolveAuthScheme(QueryAuthSchemeParams params) {
         List<AuthSchemeOption> options = new ArrayList<>();
         switch (params.operation()) {
-        case "BearerAuthOperation":
-            options.add(AuthSchemeOption.builder().schemeId("smithy.api#httpBearerAuth").build());
-            break;
-        case "OperationWithNoneAuthType":
-            options.add(AuthSchemeOption.builder().schemeId("smithy.api#noAuth").build());
-            break;
-        default:
-            options.add(AuthSchemeOption.builder().schemeId("aws.auth#sigv4")
-                    .putSignerProperty(AwsV4HttpSigner.SERVICE_SIGNING_NAME, "query-service")
-                    .putSignerProperty(AwsV4HttpSigner.REGION_NAME, params.region().id()).build());
-            break;
+            case "BearerAuthOperation":
+                options.add(AuthSchemeOption.builder().schemeId("smithy.api#httpBearerAuth").build());
+                break;
+            case "OperationWithNoneAuthType":
+                options.add(AuthSchemeOption.builder().schemeId("smithy.api#noAuth").build());
+                break;
+            default:
+                options.add(AuthSchemeOption.builder().schemeId("aws.auth#sigv4")
+                                            .putSignerProperty(AwsV4HttpSigner.SERVICE_SIGNING_NAME, "query-service")
+                                            .putSignerProperty(AwsV4HttpSigner.REGION_NAME, params.region().id()).build());
+                break;
         }
         return Collections.unmodifiableList(options);
     }

services/s3/src/test/java/software/amazon/awssdk/services/s3/internal/s3express/S3ExpressPluginTest.java

@@ -27,7 +27,7 @@
 import software.amazon.awssdk.services.s3.S3ServiceClientConfiguration;
 import software.amazon.awssdk.services.s3.auth.scheme.S3AuthSchemeProvider;
 import software.amazon.awssdk.services.s3.auth.scheme.internal.DefaultS3AuthSchemeProvider;
-import software.amazon.awssdk.services.s3.auth.scheme.internal.ModeledS3AuthSchemeProvider;
+import software.amazon.awssdk.services.s3.auth.scheme.internal.FallbackS3AuthSchemeProvider;
 import software.amazon.awssdk.services.s3.internal.S3ServiceClientConfigurationBuilder;
 import software.amazon.awssdk.services.s3.s3express.S3ExpressAuthScheme;
 
@@ -68,12 +68,12 @@ void s3Config_withDefaultS3AuthSchemeProvider_wrapsExistingProvider() {
     @Test
     void s3Config_withExistingModeledS3AuthSchemeProvider_wrapsExistingProvider() {
         S3ServiceClientConfiguration.Builder s3Config = new S3ServiceClientConfigurationBuilder()
-            .authSchemeProvider(ModeledS3AuthSchemeProvider.create());
-        assertThat(s3Config.authSchemeProvider()).isInstanceOf(ModeledS3AuthSchemeProvider.class);
+            .authSchemeProvider(FallbackS3AuthSchemeProvider.create());
+        assertThat(s3Config.authSchemeProvider()).isInstanceOf(FallbackS3AuthSchemeProvider.class);
 
         S3_EXPRESS_PLUGIN.configureClient(s3Config);
         assertThat(s3Config.authSchemeProvider()).isInstanceOf(S3ExpressAuthSchemeProvider.class);
-        assertThat(getDelegateProvider(s3Config)).isInstanceOf(ModeledS3AuthSchemeProvider.class);
+        assertThat(getDelegateProvider(s3Config)).isInstanceOf(FallbackS3AuthSchemeProvider.class);
     }
 
     private S3AuthSchemeProvider getDelegateProvider(S3ServiceClientConfiguration.Builder s3Config) {