[Bug]: Client serialization does not preserve the API's expected JSON property names and enum representation

[j-steuer]

Description

The OpenAPI specification defines the request body using camelCase property names and the lowercase enum value "available". The generated client produces a different representation.

Swagger Codegen Version

3.0.82

Language / Generator

• csharp

OpenAPI/Swagger Spec

{
    "openapi": "3.0.0",
    "info": {
        "title": "Serializer Test API",
        "version": "0.0.0"
    },
    "tags": [
        {
            "name": "test",
            "description": "Serializer test operations"
        }
    ],
    "paths": {
        "/test": {
            "post": {
                "tags": [
                    "test"
                ],
                "operationId": "post_test_xcuctqa",
                "summary": "Test model serialization",
                "requestBody": {
                    "required": true,
                    "content": {
                        "application/json": {
                            "schema": {
                                "$ref": "#/components/schemas/TestModel"
                            }
                        }
                    }
                },
                "responses": {
                    "200": {
                        "description": "OK"
                    }
                }
            }
        }
    },
    "components": {
        "schemas": {
            "TestModel": {
                "type": "object",
                "properties": {
                    "id": {
                        "type": "integer",
                        "format": "int64"
                    },
                    "firstName": {
                        "type": "string"
                    },
                    "optionalValue": {
                        "type": "string"
                    },
                    "status": {
                        "type": "string",
                        "enum": [
                            "available",
                            "pending"
                        ]
                    },
                    "tags": {
                        "type": "array",
                        "items": {
                            "$ref": "#/components/schemas/Tag"
                        }
                    }
                },
                "additionalProperties": false
            },
            "Tag": {
                "type": "object",
                "properties": {
                    "id": {
                        "type": "integer",
                        "format": "int64"
                    },
                    "name": {
                        "type": "string"
                    }
                },
                "additionalProperties": false
            }
        }
    }
}

Command Line Used

I am using a script that uses the basic command

docker run --rm \
    --user "$(id -u):$(id -g)" \
    -v "$(pwd)":/local \
    -v "$PARENT_DIR":/output \
    swaggerapi/swagger-codegen-cli-v3:3.0.82 \
    generate \
    -i /local/spec/openapi.json \
    -l "$LANG" \
    -o "/output/$OUT_NAME"

and in this case uses 'csharp' for $LANG

Steps to Reproduce

1. Generate a client using the provided specification
2. Send a request using

var body = new TestModel
{
    Id = 1,
    FirstName = "test",
    Status = TestModel.StatusEnum.Available
};

await api.PostTestXcuctqaAsync(body);

3. Observe the outgoing request body

Expected Behavior

The serialized request body should use the property names and enum values defined by the OpenAPI specification:

{
"id": 1,
"firstName": "test",
"status": "available"
}

Actual Behavior

The generated client serializes the model as:

{
"Status": "Available",
"Id": 1,
"FirstName": "test",
"OptionalValue": null,
"Tags": null
}

Related Issues / Repos

Environment

• OS: Fedora 43

Additional Context

Checklist

• I have searched the existing issues to make sure this is not a duplicate.
• I have included a minimal and reproducible spec example.
• I have explained how to reproduce the issue.
• I have specified which generator/language is affected.