[BUG] [Java] [RestClient] Custmized ObjectMapper is Ignored

[antechrestos]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• 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?
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Description

Currently with code generated, we are not able to provide a customized objectMapper used during serialization. Indeed, RestClient.Builder builds a default list of converters and then calls the consumer that currently adds the MappingJackson2HttpMessageConverter with the customized ObjectMapper at the end.

openapi-generator version

7.9.0

OpenAPI declaration file content or url

Any one.

Generation Details

Steps to reproduce

Generate any ApiClient with RestClient by providing the ObjectMapper. By breakpoint you can see that the MappingJackson2HttpMessageConverter used during serialization is the one built by default and not the one built by the generated stub.

Suggestion

See MR #20112