} else if (response.getContentException() != null) {
                logger.warn("ConfigSync request failed.", response.getContentException());
            } else {
                logger.warn("ConfigSync request failed. The response is {}", response.getContentAsString());
            }
        } catch (final IOException e) {
            logger.warn("ConfigSync request failed.", e);
        }
        return new String[0];

    @Override
    public void warn(CharSequence content) {
        if (isWarnEnabled()) {
            logger.warn(toString(content));
        }
    }

    @Override
    public void warn(CharSequence content, Throwable error) {
        if (isWarnEnabled()) {
            logger.warn(toString(content), error);
        }
    }

    @Override
    public void warn(Throwable error) {

    /**
     * @see org.apache.maven.plugin.logging.Log#warn(java.lang.CharSequence)
     */
    public void warn(CharSequence content) {
        print("warn", content);
    }

    /**
     * @see org.apache.maven.plugin.logging.Log#warn(java.lang.CharSequence, java.lang.Throwable)
     */
    public void warn(CharSequence content, Throwable error) {
        print("warn", content, error);
    }

    /**

    /**
     * @return true if the <b>warn</b> error level is enabled
     */
    boolean isWarnEnabled();

    /**
     * Send a message to the user in the <b>warn</b> error level.
     *
     * @param content
     */
    void warn(CharSequence content);

    /**
     * Send a message (and accompanying exception) to the user in the <b>warn</b> error level.<br>

    /**
     * {@return true if the <b>warn</b> error level is enabled}
     */
    boolean isWarnEnabled();

    /**
     * Sends a message to the user in the <b>warn</b> error level.
     *
     * @param content the message to log
     */
    void warn(CharSequence content);

    /**
     * Sends a message (and accompanying exception) to the user in the <b>warn</b> error level.

    public boolean isWarnEnabled() {
        return false;
    }

    public void warn(String msg) {}

    public void warn(String format, Object arg) {}

    public void warn(String format, Object... arguments) {}

    public void warn(String format, Object arg1, Object arg2) {}

    public void warn(String msg, Throwable t) {}

    public boolean isWarnEnabled(Marker marker) {
        return false;

            logger.warn("The metadata {} {}{}", metadata, errorType, msg, exception);
        } else {
            logger.warn("The metadata {} {}{}", metadata, errorType, msg);
        }
    }

    @Override
    public void artifactDescriptorInvalid(RepositoryEvent event) {
        // The exception stack trace is not really interesting here
        logger.warn(

            thumbnailQueueThread.join(10000);
        } catch (final InterruptedException e) {
            logger.warn("Thumbnail thread is timeouted.", e);
        }
        generatorList.forEach(g -> {
            try {
                g.destroy();
            } catch (final Exception e) {
                logger.warn("Failed to stop thumbnail generator.", e);
            }
        });
    }

        } catch (final Exception e) {
            logger.warn("Failed to delete UrlFilter for {}", sid, e);
        }

        try {
            // clear queue
            urlQueueService.clearCache();
            urlQueueService.delete(sid);
        } catch (final Exception e) {
            logger.warn("Failed to delete UrlQueue for {}", sid, e);
        }

        try {

                    logger.warn("Could not close a process output stream.", e);
                } finally {
                    latch.countDown();
                }
            }, "ProcessCloser-output-" + sessionId).start();

            try {
                latch.await(10, TimeUnit.SECONDS);
            } catch (final InterruptedException e) {
                logger.warn("Interrupted to wait a process.", e);