It is not possible to do a @POST with @Multipart with @RetrofitClient and WebClient

[dante-ricalde]

Describe the bug
Hi guys, @OlgaMaciaszek
I am trying to use @RetrofitClient with WebClient using the retrofit2 @Multipart annotation and it is not possible to do it (it is not working)

I am trying with the following Retrofit Client:

    @Multipart
    @POST("multipart/mono")
    fun multipartMono(@Part("file") file: Mono<org.springframework.http.codec.multipart.Part>): Mono<ResponseEntity<String>>

We want to know if there is a bug to use @Multipart with @RetrofitClient and WebClient or there is not still support for it?
if there is support for it, please can you share the link with the documentation about it?
if there is no support for it, do you have plans to support @Multipart with @RetrofitClient and WebClient?
I did not find spring documentation about how to create a org.springframework.http.codec.multipart.Part from a File, if there is documentation or examples, can you please share it to me?

Currently it is not documented how to use Multipart + Retrofit + WebClient in the official documentation of spring:
https://spring-projects-experimental.github.io/spring-cloud-square/docs/current/reference/html/index.html
https://github.com/spring-projects-experimental/spring-cloud-square
https://spring.io/blog/2021/04/13/introducing-spring-cloud-square

The examples out there are using Multipart + Retrofit + Okhttp:
https://square.github.io/retrofit/
https://futurestud.io/tutorials/retrofit-2-passing-multiple-parts-along-a-file-with-partmap
https://adinugroho.medium.com/upload-image-from-android-app-using-retrofit-2-ae6f922b184c
https://stackoverflow.com/questions/34562950/post-multipart-form-data-using-retrofit-2-0-including-image

I am looking forward to hearing from you!
Best Regards!

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