Gateway MVC forward request but with decoded parameters (%2B becomes +)

[lohoso]

Describe the bug
I use the following version of Spring Cloud Gateway MVC to forward request.
org.springframework.cloud
spring-cloud-starter-gateway-mvc
4.1.2

same description as #3272
a bug in the code of the ProxyExchangeHandlerFunction class.

	boolean encoded = containsEncodedQuery(serverRequest.uri());
	// @formatter:off
	URI url = UriComponentsBuilder.fromUri(serverRequest.uri())
			.scheme(uri.getScheme())
			.host(uri.getHost())
			.port(uri.getPort())
			.replaceQueryParams(serverRequest.params())
			.build(encoded)
			.toUri();

This is based on serverRequest.uri() to determine whether the URL has been encoded, but when constructing a new URL, the query parameter is replaced with serverRequest.params(). The reality is that serverRequest.uri() is encoded by the URI, but serverRequest.params() is not encoded.

Sample
The url as http://localhost:8083/test?q=name%3Atestname%2BState%3AFailed
In Gateway MVC will forward the rquest as
http://localhost:8083/test?q=name:testname+State:Failed, when the corrsponding service receive the request,
then + becomes space character.

For the UriComponentsBuilder, it will use HierarchicalUriComponents internally, is this related to below issue?
spring-projects/spring-framework#23025