How to change query params value in spring cloud gateway custom written GlobalFilter

I have configured spring cloud gateway in my spring boot project. My requirement is that, i want to change query params values in Custom written org.springframework.cloud.gateway.filter.GlobalFilter .

e.g postman request - http://localhost:8080/employee/message?q1=abc&q2=123

expected filter redirection - http://localhost:8080/employee/message?q1=xyz&q2=789

so that, my controller will get q1 value as xyz and q2 value as 789 instead the original values. So i want to change the value of my query params as per business case. I am able to get the query params in my filter but not able to figure out exactly how to change them.

Following is my custom filter

@Component
public class PreFilter implements GlobalFilter {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        
                ServerWebExchange modExchange = changeQueryParams(exchange);
                    return chain.filter(modExchange);
    }
    
    private static ServerWebExchange changeQueryParams(ServerWebExchange exchange)  {
        ServerHttpRequest request = exchange.getRequest();
        
        Map<String, List<String>> map = new HashMap<>();
        map.put("q1", Arrays.asList("xyz"));
        map.put("q2", Arrays.asList("789"));
        MultiValueMap<String, String> newMultiValueMap = new LinkedMultiValueMap<>(map);
        
        Builder builder = request.mutate();
        request = builder.uri(UriComponentsBuilder.fromUri(exchange.getRequest()
                .getURI())
              .replaceQueryParams(newMultiValueMap)
              .build()
              .toUri()).build();

        ServerWebExchange modifiedExchange = exchange.mutate().request(request).build();
        return modifiedExchange;
    }
}

Spring boot version = 2.7.0