[BUG][TYPESCRIPT-FETCH] Enum not generated when schema name matches ModelField pattern in oneOf

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When using the TypeScript-Fetch generator, enum schemas are not properly generated when:

1. The enum schema name follows the pattern {ModelName}{FieldName} (e.g., BuggyOneOfExampleSource for model BuggyOneOfExample with field source)
2. The enum is referenced within a oneOf construct

Instead of generating the enum constant, the generator creates a circular type reference, making the generated code unusable.

openapi-generator version

• @openapitools/openapi-generator-cli: 2.23.4
• openapi generator: 7.15.0

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Example
  version: 1.0.0
paths:
  /broken-oneof:
    get:
      summary: Broken oneOf scenario - enum not generated
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BuggyOneOfExample'
components:
  schemas:
    # BROKEN: This demonstrates the bug where enum is not generated
    # when schema name matches ModelField pattern and is used in oneOf
    BuggyOneOfExample:
      type: object
      properties:
        source:
          oneOf:
            - $ref: '#/components/schemas/BuggyOneOfExampleSource'
            - $ref: '#/components/schemas/EmptyValue'

    # This enum will NOT be generated due to the bug (name matches ModelField pattern)
    BuggyOneOfExampleSource:
      type: string
      enum:
        - MANUAL
        - SCANNER
        - OTHER

    # Empty value enum for oneOf scenarios
    EmptyValue:
      enum:
      - ''

Generation Details

I've created a simple repository to replicate the issue https://github.com/MrMarble/openapi-typescript-generator-one-of

# Install dependencies
npm install

# Generate TypeScript client
npm run generate

Configuration (openapitools.json):

{
  "$schema": "./node_modules/@openapitools/openapi-generator-cli/config.schema.json",
  "spaces": 2,
  "generator-cli": {
    "version": "7.15.0",
    "generators": {
      "Example": {
        "generatorName": "typescript-fetch",
        "output": "src/generated",
        "inputSpec": "openapi.yml",
        "additionalProperties": {
          "supportsES6": "true",
          "withoutRuntimeChecks": true
        }
      }
    }
  }
}

Steps to reproduce

1. Create an OpenAPI spec with a model that has a field using oneOf
2. Reference an enum schema where the schema name follows the pattern {ModelName}{FieldName}
3. Generate TypeScript code using the typescript-fetch generator
4. Observe that the enum constant is not generated, only a circular type reference

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/14763

Suggest a fix

I tried playing around with the templates and was unable to make it work, so maybe the issue is in the logic that parses the schemas?

Start with the typescript-fetch generator and reproduce the case using the linked repository and its npm run generate command. Trace how the oneOf schema references are parsed and compare the generated output with the expected enum constant; done means the enum is generated without a circular type reference.