multipart body request is empty when using BeforeFilterFunctions rewritePath

Describe the bug
I'm using spring gateway mvc as a simple gateway to route input request to backend app. My route config rewrite the host and the url base path.
It works well except for multipart requests. With a multipart request, the output body is empty.
After some research in my side to identify the problem, it seems the rewritePath function is the root cause. If I delete it of my route, multipart requests works.
I'm using the function rewritePath in org.springframework.cloud.gatexay.server.mvc.BeforeFilterFunctions in a RouterFunction policy.

Sample

To prove the problem, I reproduced the case with this simple code.

@Configuration
public class RouterConfiguration {
    private static final String WILDCARD = "/**";
    private static final String SEGMENT_TO_INCLUDE_REGEX = "(?<segment>.*)";
    private static final String SEGMENT_TO_ADD_REGEX = "${segment}";
    
    @Bean
    public RouterFunctions.Builder routerFunctionsBuilder() {
        return RouterFunctions.route();
    }

    @Bean
    public RouterFunction<ServerResponse> buildRoutes(RouterFunctions.Builder routerFunctionsBuilder) {
        var destinationHost = URI.create("http://localhost:9008/");
        
        routerFunctionsBuilder
                .POST("multipart" + WILDCARD, HandlerFunctions.http(destinationHost)) // multipart works with this line only
                // multipart don't work anymore in adding the filter (body is empty)
                .before(BeforeFilterFunctions.rewritePath("multipart" + SEGMENT_TO_INCLUDE_REGEX, "/api/multipart" + SEGMENT_TO_ADD_REGEX));

        return routerFunctionsBuilder.build();
    }

}

Versions
Spring Boot : 3.3.0
spring cloud starter gateway mvc : 4.1.5

related issues but not solved : 3449

** Expectations **
rewritePath function works with multipart requests

Start with the RouterFunction sample and inspect BeforeFilterFunctions.rewritePath alongside HandlerFunctions.http, reproducing the multipart request with and without the filter. Trace why the rewritten route forwards an empty body, then verify that multipart content reaches the backend while the path is rewritten to /api/multipart.