There is no documentation for `adaptCachedBody`

[1chz]

Is your feature request related to a problem? Please describe.
There is no documentation for BeforeFilterFunctions.adaptCachedBody.

Describe the solution you'd like
We need official documentation for BeforeFilterFunctions.adaptCachedBody and MvcUtils.cacheAndReadBody.

Describe alternatives you've considered
None

Additional context
Hello. I recently started developing an API Gateway at my company. Since we are using JDK 21 and Spring Boot 3+, we chose spring-cloud-gateway-mvc to take advantage of virtual threads.

One of our requirements was to read the request body to generate an HMAC. However, since the request body can only be read once, we needed to cache it. I checked all the official documentation for spring-cloud-gateway-mvc, but couldn't find anything relevant. I had to search issues in this repository and analyze the spring-cloud-gateway-mvc source code directly.

Here are the links to the documents I referred to.
https://docs.spring.io/spring-cloud-gateway/reference/spring-cloud-gateway-server-mvc.html