I’m migrating an application from Netflix/Zuul to Spring Cloud Gateway:

public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    ServletServerHttpRequest serverHttpRequest = (ServletServerHttpRequest)exchange.getRequest();
    ServletServerHttpResponse serverHttpResponse = (ServletServerHttpResponse)exchange.getResponse();
    if (shouldFilter(exchange)) {
        try {
            log.debug("Invoking authorization interceptor");
            if (!checkRequest(
                    serverHttpRequest.getServletRequest(),
                    serverHttpResponse.getServletResponse(),
                    null)) {
                return Mono.error(new RuntimeException("Invalid request"));
            }
            return chain.filter(exchange);
        } catch (Exception exception) {
            log.error(ERROR_MESSAGE, exception);
            return Mono.error(exception);
        }
    }
    return Mono.empty();
}

The test case I wrote is as follows:

private GatewayFilterChain filterChain
private static ServerWebExchange exchange;

def setup() {
    exchange = mock(ServerWebExchange.class)
    ServerHttpRequest request = mock(ServerHttpRequest.class)
    ServerHttpResponse response = mock(ServerHttpResponse.class)
    filterChain = mock(GatewayFilterChain.class)
    when(filterChain.filter(exchange)).thenReturn(Mono.empty())
    when(exchange.getRequest()).thenReturn(request)
    when(exchange.getResponse()).thenReturn(response)
}

However, when testing, I’m getting the following error:

java.lang.ClassCastException: class org.springframework.http.server.reactive.ServerHttpRequest$MockitoMock$6YiKyP1Z cannot be cast to class org.springframework.http.server.ServletServerHttpRequest (org.springframework.http.server.reactive.ServerHttpRequest$MockitoMock$6YiKyP1Z and org.springframework.http.server.ServletServerHttpRequest are in unnamed module of loader 'app')

I do have to stick with HttpServletRequest and HttpServletResponse in jakarta, otherwise would be a nightmare to re-implement the downstream service. What would be the best way to cast/convert ServerHttpRequest to HttpServletRequest?