@Controller("/books")
class BooksController {
    @Get("/{isbn}")
    HttpResponse find(String isbn) {
        if (isbn == "1680502395") {
            Map<String, Object> m = new HashMap<>()
            m.put("status", 401)
            m.put("error", "Unauthorized")
            m.put("message", "No message available")
            m.put("path", "/books/"+isbn)
            return HttpResponse.status(HttpStatus.UNAUTHORIZED).body(m)
        return HttpResponse.ok(new Book("1491950358", "Building Microservices"))
    }
}

    @Test
    public void afterAnHttpClientExceptionTheResponseBodyCanBeBoundToAPOJO() {
        try {
            client.toBlocking().exchange(HttpRequest.GET("/books/1680502395"),
                    Argument.of(Book.class), (1)
                    Argument.of(CustomError.class)); (2)
        } catch (HttpClientResponseException e) {
            assertEquals(HttpStatus.UNAUTHORIZED, e.getResponse().getStatus());
            Optional<CustomError> jsonError = e.getResponse().getBody(CustomError.class);
            assertTrue(jsonError.isPresent());
            assertEquals("Unauthorized", jsonError.get().error);
            assertEquals("No message available", jsonError.get().message);
            assertEquals("/books/1680502395", jsonError.get().path);
        }
    }

        "after an httpclient exception the response body can be bound to a POJO" {
            try {
                client.toBlocking().exchange(HttpRequest.GET<Any>("/books/1680502395"),
                        Argument.of(Book::class.java), (1)
                        Argument.of(CustomError::class.java)) (2)
            } catch (e: HttpClientResponseException) {
                e.response.status shouldBe HttpStatus.UNAUTHORIZED
            }