如何在Spring Cloud Gateway中有条件地路由到不同的URL？有没有参考样本？

@Configuration
public class GatewayConfig {

    @Bean
    public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
        return builder.routes()
                .route("path_route", r -> r.path("/api/**")
                        .filters(f -> f.addRequestHeader("X-Request-Test", "TestHeader"))
                        .uri("http://example.com"))
                .build();
    }
}