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fix(normalizer): support OAS 3.1 annotated enums (oneOf + const) for consistent enum generation (C#) #23869

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fix(normalizer): support OAS 3.1 annotated enums (oneOf + const) for consistent enum generation (C#) #23869

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9fbf404
Introducing Annotated Enum with const
nagabalaji-b May 22, 2026
51e0b0f
fix: support OpenAPI 3.1 const in annotated enum normalization
nagabalaji-b May 25, 2026
ba6d6a2
fix(docs): use forward slashes in path separators for cross-platform …
nagabalaji-b May 25, 2026
553b721
revert: remove unrelated doc file changes from PR scope
nagabalaji-b May 26, 2026
3496c3b
refactor(normalizer): extract definesEnum variable per reviewer sugge…
nagabalaji-b May 26, 2026
55450c4
fix(normalizer): preserve x-enum-deprecated for oneOf/anyOf const enums
nagabalaji-b Jun 5, 2026
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2 changes: 1 addition & 1 deletion docs/generators/fsharp-functions.md
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Expand Up @@ -34,7 +34,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
|prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
|sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
|sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
|sourceFolder|source folder for generated code| |OpenAPI/src|
|sourceFolder|source folder for generated code| |OpenAPI\src|
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@Mattias-Sehlstedt Mattias-Sehlstedt May 25, 2026

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Are these path changes intentional?


## IMPORT MAPPING

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2 changes: 1 addition & 1 deletion docs/generators/fsharp-giraffe-server.md
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Expand Up @@ -30,7 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
|packageVersion|F# package version.| |1.0.0|
|returnICollection|Return ICollection<T> instead of the concrete type.| |false|
|sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
|sourceFolder|source folder for generated code| |OpenAPI/src|
|sourceFolder|source folder for generated code| |OpenAPI\src|
|useCollection|Deserialize array types to Collection<T> instead of List<T>.| |false|
|useDateTimeOffset|Use DateTimeOffset to model date-time properties| |false|
|useSwashbuckle|Uses the Swashbuckle.AspNetCore NuGet package for documentation.| |false|
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2 changes: 1 addition & 1 deletion docs/generators/jaxrs-cxf-client.md
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Expand Up @@ -70,7 +70,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
|snapshotVersion|Uses a SNAPSHOT version.|<dl><dt>**true**</dt><dd>Use a SnapShot Version</dd><dt>**false**</dt><dd>Use a Release Version</dd></dl>|null|
|sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
|sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
|sourceFolder|source folder for generated code| |src/gen/java|
|sourceFolder|source folder for generated code| |src\gen\java|
|testOutput|Set output folder for models and APIs tests| |${project.build.directory}/generated-test-sources/openapi|
|useAbstractionForFiles|Use alternative types instead of java.io.File to allow passing bytes without a file on disk.| |false|
|useBeanValidation|Use BeanValidation API annotations| |false|
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4 changes: 2 additions & 2 deletions docs/generators/swift5.md
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Expand Up @@ -52,13 +52,13 @@ These options may be applied as additional-properties (cli) or configOptions (pl
|responseAs|Optionally use libraries to manage response. Currently PromiseKit, RxSwift, Result, Combine, AsyncAwait are available.| |null|
|sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
|sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
|swiftPackagePath|Set a custom source path instead of OpenAPIClient/Classes/OpenAPIs.| |null|
|swiftPackagePath|Set a custom source path instead of OpenAPIClient\Classes\OpenAPIs.| |null|
|swiftUseApiNamespace|Flag to make all the API classes inner-class of {{projectName}}API| |null|
|useBacktickEscapes|Escape reserved words using backticks (default: false)| |false|
|useClasses|Use final classes for models instead of structs (default: false)| |false|
|useCustomDateWithoutTime|Uses a custom type to decode and encode dates without time information to support OpenAPIs date format (default: false)| |false|
|useJsonEncodable|Make models conform to JSONEncodable protocol (default: true)| |true|
|useSPMFileStructure|Use SPM file structure and set the source path to Sources/{{projectName}} (default: false).| |null|
|useSPMFileStructure|Use SPM file structure and set the source path to Sources\{{projectName}} (default: false).| |null|
|validatable|Make validation rules and validator for model properties (default: true)| |true|

## IMPORT MAPPING
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15 changes: 10 additions & 5 deletions modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
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Expand Up @@ -1620,10 +1620,15 @@ protected Schema simplifyComposedSchemaWithEnums(Schema schema, List<Object> sub

Schema subSchema = ModelUtils.getReferencedSchema(openAPI, (Schema) item);

// Check if this sub-schema has an enum (with one or more values)
if (subSchema.getEnum() == null || subSchema.getEnum().isEmpty()) {
// Check if this sub-schema has an enum or const value (OpenAPI 3.1 uses const for single-value enums)
List<Object> subSchemaEnumValues = subSchema.getEnum();
if ((subSchemaEnumValues == null || subSchemaEnumValues.isEmpty()) && subSchema.getConst() == null) {
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@Mattias-Sehlstedt Mattias-Sehlstedt May 25, 2026 •
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Rather than doing (subSchemaEnumValues == null || subSchemaEnumValues.isEmpty()) twice, could we extract this to a variable boolean definesEnum = ModelUtils.hasEnum(subSchema) and then have

if (!definesEnum && subSchema.getConst() == null) {

This could allow use to skip the comments almost entirely and instead allow the variable/method names be the explanation themselves.

return schema;
}
// If const is present but enum is not, treat const as a single enum value
if ((subSchemaEnumValues == null || subSchemaEnumValues.isEmpty()) && subSchema.getConst() != null) {
subSchemaEnumValues = Arrays.asList(subSchema.getConst());
}

// Ensure all sub-schemas have the same type (if type is specified)
if(subSchema.getTypes() != null && subSchema.getTypes().size() > 1) {
Expand All @@ -1639,17 +1644,17 @@ protected Schema simplifyComposedSchemaWithEnums(Schema schema, List<Object> sub
}
}
// Add all enum values from this sub-schema to our collection
if(subSchema.getEnum().size() == 1) {
if(subSchemaEnumValues.size() == 1) {
String description = subSchema.getTitle() == null ? "" : subSchema.getTitle();
if(subSchema.getDescription() != null) {
if(!description.isEmpty()) {
description += " - ";
}
description += subSchema.getDescription();
}
enumValues.put(subSchema.getEnum().get(0), description);
enumValues.put(subSchemaEnumValues.get(0), description);
} else {
for(Object e: subSchema.getEnum()) {
for(Object e: subSchemaEnumValues) {
enumValues.put(e, "");
}
}
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7 changes: 4 additions & 3 deletions modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
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Expand Up @@ -1536,9 +1536,10 @@ public void testOpenAPINormalizerSimplifyOneOfAnyOf31Spec() {
assertEquals(schema14.getType(), null);

Schema schema16 = openAPI.getComponents().getSchemas().get("TypeIntegerWithOneOf");
assertEquals(schema16.getOneOf().size(),3);
assertEquals(((Schema) schema16.getOneOf().get(0)).getConst(), 1);
assertEquals(((Schema) schema16.getOneOf().get(0)).getDeprecated(), true);
// After normalization, oneOf with const values should be simplified to enum
assertEquals(schema16.getOneOf(), null);
assertEquals(schema16.getEnum().size(), 3);
assertEquals(schema16.getEnum().get(0), 1);
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@JPPortier JPPortier May 28, 2026

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(I'm not repo maintainer but the PR is something I was thinking about myself: so thank you)

The test against deprecated (https://github.com/nagabalaji-b/openapi-generator/blob/3496c3b7cffbc0cdc728cc77bd64708b8ba6ae9a/modules/openapi-generator/src/test/resources/3_1/simplifyOneOfAnyOf_test.yaml#L133) is lost here (and the information from schema too)

Here, seems it is not possible with current enum support implementation ("simple" list of values and optional list of descriptions with x-enum-descriptions) to support enum as "schema" enabling to keep all "schemas" related information with no loss.

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@wing328 wing328 Jun 5, 2026

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@nagabalaji-b can you please take a look and add back the deprecated test?

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@nagabalaji-b nagabalaji-b Jun 5, 2026

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@wing328 Done. I added back the deprecated test coverage:

Code change: Modified simplifyComposedSchemaWithEnums() to collect and preserve per-value deprecated flags from OAS 3.1 oneOf/anyOf + const sub-schemas into x-enum-deprecated extension.

Test assertion: Added explicit checks in testOpenAPINormalizerSimplifyOneOfAnyOf31Spec() for TypeIntegerWithOneOf schema:

Verifies x-enum-deprecated list size = 3
Verifies flags match expected values: [true, false, false] (first enum value was deprecated in the original YAML)
Validation: Ran the test locally and confirmed BUILD SUCCESS.

The deprecated metadata from the annotated enum pattern (oneOf + const) is now preserved through normalization, so generators can access it via the x-enum-deprecated extension.


Schema schema18 = openAPI.getComponents().getSchemas().get("OneOfNullAndRef3");
// original oneOf removed and simplified to just $ref (oneOf sub-schema) instead
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