Spring AI Allow custom fields on ChatCompletion

As mentioned in this discussion the recommendation according to the ref docs is to use the OpenAI API when using Perplexity.

Perplexity adds fields to the ChatCompletion like citations. Right now there is no way to deserialize and expose these additional fields.

Expected Behavior

An API to define custom fields e.g. custom metadata fields?

Current Behavior

Additional fields are swallowed silently.

Context

https://docs.spring.io/spring-ai/reference/api/chat/perplexity-chat.html

Comment From: dev-jonghoonpark

related perplexity doc: https://docs.perplexity.ai/api-reference/chat-completions#response-citations

Comment From: sunyuhan1998

Yes, this is also a problem that many people encounter. Many models claim that their interfaces follow the OpenAI API standards, but in fact there are some subtle differences with the OpenAI API. However, at present, Spring AI directly deserializes the return results of the model interface into ChatCompletionChunk, lacking some customized means.