[BUG][PHP] hydra model properties with @ prefix are removed which can result in method duplicates and invalid classes

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?

Description

When generating PHP client classes from a schema generated by API Platform you can get invalid PHP classes because of clashing method names. A Hydra model can have "@id" and "id" as properties resulting in two clashing getId methods

generator version

3.0.35-SNAPSHOT
3.0.34

OpenAPI declaration file content or url

Book.jsonld-book.read:
      type: object
      description: ''
      externalDocs:
        url: 'https://schema.org/Book'
      properties:
        '@context':
          readOnly: true
          oneOf:
            -
              type: string
            -
              type: object
              properties:
                '@vocab':
                  type: string
                hydra:
                  type: string
                  enum: ['http://www.w3.org/ns/hydra/core#']
              required:
                - '@vocab'
                - hydra
              additionalProperties: true
        '@id':
          readOnly: true
          type: string
        '@type':
          readOnly: true
          type: string
        id:
          readOnly: true
          type: string
          format: uuid
          nullable: true

Steps to reproduce

1. wget https://repo1.maven.org/maven2/io/swagger/codegen/v3/swagger-codegen-cli/3.0.34/swagger-codegen-cli-3.0.34.jar -O swagger-codegen-cli.jar
2. wget https://gist.githubusercontent.com/warmwaterkruik/d6836d463ef765c8ae16a0ff53f68d3f/raw/f3cc01c42a87b79d101a2326d12142ff8a362260/bookshop-api.yaml
3. java -jar swagger-codegen-cli.jar generate --lang php --input-spec bookshop-api.yaml --output ${PWD}
4. Check the generated file BookJsonld.php - This is invalid because of double getId() methods

Suggest a fix

Pull request opened with fix: https://github.com/swagger-api/swagger-codegen-generators/pull/1042

Start with the provided Hydra schema and reproduce the issue using swagger-codegen-cli.jar with the PHP generator. Inspect the generated BookJsonld.php and the generator path responsible for handling @-prefixed properties. Done means the schema no longer produces duplicate getId() methods or an invalid PHP class; a pull request is already linked in the issue.