assertEquals(400, exception1.getStatusCode());
        assertEquals(401, exception2.getStatusCode());
        assertEquals(500, exception3.getStatusCode());

        assertTrue(exception1.getStatusCode() != exception2.getStatusCode());
        assertTrue(exception2.getStatusCode() != exception3.getStatusCode());
    }

    public void test_exceptionWithLongMessage() {

        try (CloseableHttpResponse response = httpClient.execute(httpPost)) {
            if (response.getStatusLine().getStatusCode() != Constants.OK_STATUS_CODE) {
                logger.error("Failed to access {}, code: {}.", url, response.getStatusLine().getStatusCode());
                return null;
            }

            data.setContent(EntityUtils.toString(response.getEntity(), Charsets.UTF_8));

                message = "[" + errorCode + "] Failed to access to Web API.";
                logger.warn(message, e);
            }
            response.sendError(e.getStatusCode(), message);
        }
    }

    /**
     * Processes API requests to the search engine.
     * Handles both regular API calls and plugin requests.
     *

        } catch (final WebApiException e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Failed to process a popularWord request.", e);
            }
            writeJsonResponse(e.getStatusCode(), e);
        } catch (final Exception e) {
            if (logger.isDebugEnabled()) {
                logger.debug("Failed to process a popularWord request.", e);
            }

            // get a content
            final HttpResponse response = executeHttpClient(httpGet);
            httpEntity = response.getEntity();

            final int httpStatusCode = response.getStatusLine().getStatusCode();
            if (httpStatusCode == 200) {

                // check file size
                final Header contentLengthHeader = response.getFirstHeader("Content-Length");