[BUG] [Rust Server] Generator type is incorrect for objects with both properties and additionalProperties specified

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
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Description

Generator type is incorrect for objects with both properties and additionalProperties specified

openapi-generator version

5.0.x

OpenAPI declaration file content or url

ObjectParam:
  type: object
  required:
    - requiredParam
  properties:
    requiredParam:
      type: boolean
    optionalParam:
      type: integer

•  additionalProperties: true
  

Command line used for generation

bin/rust-server-petstore.sh

Steps to reproduce

additionalProperties is ignored in the generated code.

Related issues/PRs

#5515
https://github.com/OpenAPITools/openapi-generator/issues/5515

Suggest a fix

Run bin/rust-server-petstore.sh with the ObjectParam schema shown and inspect the generated Rust type. Compare the result with the expected handling of additionalProperties alongside requiredParam and optionalParam; done means additionalProperties is represented rather than ignored.