public static List<String> extractLinks(String content) {
        if (content == null || content.length() == 0) {
            return Collections.emptyList();
        }

        List<String> extractions = new ArrayList<>();
        final Matcher matcher = LINKS_PATTERN.matcher(content);
        while (matcher.find()) {
            extractions.add(matcher.group());
        }
        return extractions;

    }
@Test
    public void testExtractLinksHttp() {
        List<String> links = RegexUtils.extractLinks(
                "Test with http://www.nutch.org/index.html is it found? " +
                        "What about www.google.com at http://www.google.de " +
                        "A longer URL could be http://www.sybit.com/solutions/portals.html");

        assertTrue(links.size() == 3, "Url not found!");
        assertEquals("http://www.nutch.org/index.html", links.get(0), "Wrong URL");
        assertEquals("http://www.google.de", links.get(1), "Wrong URL");
        assertEquals("http://www.sybit.com/solutions/portals.html", links.get(2),
                "Wrong URL");
    }