Add configuration option and documentation for type alias generation

Based on review feedback:
1. Improved template comment to be more specific about "deduplicated inline model schemas"
2. Added configuration option 'generateTypeAliasesForDedupedSchemas' (defaults to true)
   - Added constant to CodegenConstants
   - Added boolean field to AbstractGoCodegen
   - Added CLI option to GoClientCodegen
   - Made type alias generation conditional on this flag
3. Added documentation to Go generator docs explaining the new option

The feature can now be disabled by setting:
--additional-properties=generateTypeAliasesForDedupedSchemas=false

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: AriehSchneier

docs/generators/go.md

@@ -23,6 +23,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response. With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enums are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |generateInterfaces|Generate interfaces for api classes| |false|
 |generateMarshalJSON|Generate MarshalJSON method| |true|
+|generateTypeAliasesForDedupedSchemas|Generate type aliases for deduplicated inline model schemas. When the InlineModelResolver deduplicates inline schemas with identical structures, this option creates type aliases using the original inline model names, preserving naming context from the OpenAPI specification.| |true|
 |generateUnmarshalJSON|Generate UnmarshalJSON method| |true|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |isGoSubmodule|whether the generated Go module is a submodule| |false|

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

@@ -449,6 +449,9 @@ public static enum ENUM_PROPERTY_NAMING_TYPE {camelCase, PascalCase, snake_case,
 
     public static final String GENERATE_UNMARSHAL_JSON = "generateUnmarshalJSON";
     public static final String GENERATE_UNMARSHAL_JSON_DESC = "Generate UnmarshalJSON method";
+
+    public static final String GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS = "generateTypeAliasesForDedupedSchemas";
+    public static final String GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS_DESC = "Generate type aliases for deduplicated inline model schemas (Go only)";
     public static final String MAX_ATTEMPTS_FOR_RETRY = "maxAttemptsForRetry";
 
     public static final String WAIT_TIME_OF_THREAD = "waitTimeMillis";

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

@@ -58,6 +58,8 @@ public abstract class AbstractGoCodegen extends DefaultCodegen implements Codege
     @Setter
     protected boolean generateUnmarshalJSON = true;
     @Setter
+    protected boolean generateTypeAliasesForDedupedSchemas = true;
+    @Setter
     protected boolean useDefaultValuesForRequiredVars = false;
 
     @Setter
@@ -792,20 +794,22 @@ public ModelsMap postProcessModels(ModelsMap objs) {
 
             // Collect reused model properties for type alias generation
             Map<String, String> typeAliasesMap = new LinkedHashMap<>();
-            
+
             for (CodegenProperty cp : codegenProperties) {
-                // Swap dataType and dataTypeAlias so fields use the alias name
-                swapDataTypeAndAlias(cp, typeAliasesMap);
-                
-                // Also swap for array items and update the array's dataType
-                if (cp.items != null && cp.items.dataTypeAlias != null) {
-                    String oldItemsDataType = cp.items.dataType;
-                    swapDataTypeAndAlias(cp.items, typeAliasesMap);
-                    String newItemsDataType = cp.items.dataType;
-                    
-                    // Update the array's dataType to use the new items dataType
-                    if (cp.dataType != null && cp.dataType.contains(oldItemsDataType)) {
-                        cp.dataType = cp.dataType.replace(oldItemsDataType, newItemsDataType);
+                // Swap dataType and dataTypeAlias so fields use the alias name (only if feature is enabled)
+                if (generateTypeAliasesForDedupedSchemas) {
+                    swapDataTypeAndAlias(cp, typeAliasesMap);
+
+                    // Also swap for array items and update the array's dataType
+                    if (cp.items != null && cp.items.dataTypeAlias != null) {
+                        String oldItemsDataType = cp.items.dataType;
+                        swapDataTypeAndAlias(cp.items, typeAliasesMap);
+                        String newItemsDataType = cp.items.dataType;
+
+                        // Update the array's dataType to use the new items dataType
+                        if (cp.dataType != null && cp.dataType.contains(oldItemsDataType)) {
+                            cp.dataType = cp.dataType.replace(oldItemsDataType, newItemsDataType);
+                        }
                     }
                 }
 
@@ -889,8 +893,8 @@ public ModelsMap postProcessModels(ModelsMap objs) {
                 model.vendorExtensions.putIfAbsent("x-go-generate-unmarshal-json", true);
             }
 
-            // Convert type aliases map to list for template usage
-            if (!typeAliasesMap.isEmpty()) {
+            // Convert type aliases map to list for template usage (only if feature is enabled)
+            if (generateTypeAliasesForDedupedSchemas && !typeAliasesMap.isEmpty()) {
                 List<Map<String, String>> typeAliases = new ArrayList<>();
                 for (Map.Entry<String, String> entry : typeAliasesMap.entrySet()) {
                     if (!entry.getKey().equals(entry.getValue())) {

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

@@ -153,6 +153,7 @@ public GoClientCodegen() {
         cliOptions.add(CliOption.newBoolean(WITH_GO_MOD, "Generate go.mod and go.sum", true));
         cliOptions.add(CliOption.newBoolean(CodegenConstants.GENERATE_MARSHAL_JSON, CodegenConstants.GENERATE_MARSHAL_JSON_DESC, true));
         cliOptions.add(CliOption.newBoolean(CodegenConstants.GENERATE_UNMARSHAL_JSON, CodegenConstants.GENERATE_UNMARSHAL_JSON_DESC, true));
+        cliOptions.add(CliOption.newBoolean(CodegenConstants.GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS, CodegenConstants.GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS_DESC, true));
 
         CliOption enumUnknownDefaultCaseOpt = CliOption.newBoolean(
                 CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE,
@@ -312,6 +313,10 @@ public void processOpts() {
             setGenerateUnmarshalJSON(Boolean.parseBoolean(additionalProperties.get(CodegenConstants.GENERATE_UNMARSHAL_JSON).toString()));
         }
 
+        if (additionalProperties.containsKey(CodegenConstants.GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS)) {
+            setGenerateTypeAliasesForDedupedSchemas(Boolean.parseBoolean(additionalProperties.get(CodegenConstants.GENERATE_TYPE_ALIASES_FOR_DEDUPED_SCHEMAS).toString()));
+        }
+
 
         // add lambda for mustache templates to handle oneOf/anyOf naming
         // e.g. []string => ArrayOfString

modules/openapi-generator/src/main/resources/go/model_simple.mustache

@@ -1,5 +1,5 @@
 {{#vendorExtensions.x-go-has-type-aliases}}
-// Type aliases for reused model types
+// Type aliases for deduplicated inline model schemas
 {{#vendorExtensions.x-go-type-aliases}}
 type {{aliasName}} = {{originalType}}
 {{/vendorExtensions.x-go-type-aliases}}