[Fixed] How come Spring Webclient onStatus is not applicable for HttpStatus::is4xxClientError? – Spring

The Solutions:

Solution 1: Predicate Type mismatch

In the provided code, the `onStatus` method expects a `Predicate` as its first argument, but `HttpStatus::is4xxClientError` is a static method that takes a `HttpStatusCode` as its argument. To resolve this issue, change the method reference to `HttpStatusCode::is4xxClientError` instead of `HttpStatus::is4xxClientError`:

// send getMap WMS to geoserver
public Mono<byte[]> getMap(String requestURL) {

    return geoserverWebClient
            .get()
            .uri(requestURL)
            .retrieve()
            .onStatus(HttpStatusCode::is4xxClientError,
                    error -> Mono.error(new RuntimeException("API not found")))
            .bodyToMono(byte[].class);
}