SpringBoot Docker response 407 is not handled correctly resulting in no error message

HttpClientTransport has the following code:

    private Response execute(HttpUriRequest request) {
        try {
            beforeExecute(request);
            ClassicHttpResponse response = this.client.executeOpen(this.host, request, null);
            int statusCode = response.getCode();
            if (statusCode >= 400 && statusCode <= 500) {
                byte[] content = readContent(response);
                response.close();
                Errors errors = (statusCode != 500) ? deserializeErrors(content) : null;
                Message message = deserializeMessage(content);
                throw new DockerEngineException(this.host.toHostString(), request.getUri(), statusCode,
                        response.getReasonPhrase(), errors, message);
            }
            return new HttpClientResponse(response);
        }
        catch (IOException | URISyntaxException ex) {
            throw new DockerConnectionException(this.host.toHostString(), ex);
        }
    }

But it appears that Docker returns 407 response with a plain text message when Enforced Sign-In is required. It would be helpful if we could surface that error.