Can't have @PostRequest with formdata in spring-cloud-gateway-mvc application

[tschut]

Describe the bug
I'm on spring-cloud-gateway-server-mvc version 4.1.2.

In my application I have a simple controller:

@RestController
@RequestMapping("/internal/test")
class TestController {
    @PostMapping
    fun test(@RequestBody(required = false) body: String?) {
        println("####### body: $body")
    }
}

I then use curl to call this endpoint (note curl will add Content-Type: application/x-www-form-urlencoded):

curl "http://localhost:8080/internal/test" -d "foo=bar"

and the output is

####### body: null

When I add the property spring.cloud.gateway.mvc.form-filter.enabled: false it works again and the output is as expected.

Is having a @PostMapping with form data supposed to work in an application with spring-cloud-gateway?
I found this in the docs https://docs.spring.io/spring-cloud-gateway/reference/spring-cloud-gateway-server-mvc/working-with-servlets-and-filters.html#page-title, but it's not clear to me how this would apply to a Controller and not a Filter.

When debugging I found that at this point, request.getParameterMap() returns an empty map instead of a map with 1 entry (as it does when the form filter is disabled). Note that at this point, request is the request as it was wrapped by FormFilter.