@Override
    public String processLink(String link) {
        var externalLink = externalUrlSupplier.getRaw();
        if (StringUtils.isBlank(link)) {
            return link;
        }
        if (externalLink == null || !linkInSite(externalLink, link)) {
            return link;
        }

        return append(externalLink.toString(), link);
    }
@Test
    void processWhenLinkIsEmpty() {
        assertThat(externalLinkProcessor.processLink(null)).isNull();
        assertThat(externalLinkProcessor.processLink("")).isEmpty();
    }