Add granular allowlist for underscores in member names

Author: RanVaknin

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

@@ -363,6 +363,11 @@ public class CustomizationConfig {
      */
     private boolean enableEndpointProviderUriCaching;
 
+    /**
+     * List of specific shape or member names that are allowed to contain underscores.
+     */
+    private List<String> allowedUnderscoreNames = new ArrayList<>();
+
     private CustomizationConfig() {
     }
 
@@ -951,4 +956,12 @@ public boolean getEnableEndpointProviderUriCaching() {
     public void setEnableEndpointProviderUriCaching(boolean enableEndpointProviderUriCaching) {
         this.enableEndpointProviderUriCaching = enableEndpointProviderUriCaching;
     }
+
+    public List<String> getAllowedUnderscoreNames() {
+        return allowedUnderscoreNames;
+    }
+
+    public void setAllowedUnderscoreNames(List<String> allowedUnderscoreNames) {
+        this.allowedUnderscoreNames = allowedUnderscoreNames;
+    }
 }

codegen/src/main/java/software/amazon/awssdk/codegen/naming/DefaultNamingStrategy.java

@@ -28,6 +28,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
@@ -498,6 +499,11 @@ private void validateCustomerVisibleName(String name, String location) {
         }
 
         if (name.contains("_")) {
+            List<String> allowedNames = customizationConfig.getAllowedUnderscoreNames();
+            if (allowedNames != null && allowedNames.contains(name)) {
+                return;
+            }
+
             UnderscoresInNameBehavior behavior = customizationConfig.getUnderscoresInNameBehavior();
 
             String supportedBehaviors = Arrays.toString(UnderscoresInNameBehavior.values());

codegen/src/test/java/software/amazon/awssdk/codegen/naming/DefaultNamingStrategyTest.java

@@ -25,6 +25,7 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
 import org.junit.Before;
@@ -337,6 +338,36 @@ public void validateAllowsUnderscoresWithCustomization() {
         strategy.validateCustomerVisibleNaming(model);
     }
 
+    @Test
+    public void validateAllowsSpecificUnderscoresWithAllowlist() {
+        CustomizationConfig customization =
+            CustomizationConfig.create();
+        customization.setAllowedUnderscoreNames(Arrays.asList("checksumXXHASH3_64", "foo_bar"));
+
+        NamingStrategy strategy = new DefaultNamingStrategy(serviceModel, customization);
+        Metadata metadata = new Metadata();
+
+        metadata.setAsyncBuilderInterface("foo_bar");
+        IntermediateModel model = new IntermediateModel();
+        model.setMetadata(metadata);
+        strategy.validateCustomerVisibleNaming(model);
+    }
+
+    @Test
+    public void validateRejectsSpecificUnderscoresWithAllowlist() {
+        CustomizationConfig customization =
+            CustomizationConfig.create();
+        customization.setAllowedUnderscoreNames(Arrays.asList("checksumXXHASH3_64", "foo_bar"));
+
+        NamingStrategy strategy = new DefaultNamingStrategy(serviceModel, customization);
+        Metadata metadata = new Metadata();
+
+        metadata.setAsyncBuilderInterface("fizz_buzz");
+        IntermediateModel model = new IntermediateModel();
+        model.setMetadata(metadata);
+        assertThatThrownBy(() -> strategy.validateCustomerVisibleNaming(model)).isInstanceOf(RuntimeException.class);
+    }
+
     @Test
     public void getSigningNameForEnvironmentVariables_convertsDashAndUppercases() {
         when(serviceModel.getMetadata()).thenReturn(serviceMetadata);