public String extractVersion(String rawXml) {
        Matcher m = p.matcher(rawXml);

        if (m.find()) {
            return m.group(1);
        }
        throw new IllegalArgumentException("Impossible to extract version from the file");
    }
@Test
    public void extractVersionWhenXmlPrologIsPresent() {
        String version = instance.extractVersion("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                                                         "<ScenarioSimulationModel version=\"1.1\">");
        assertThat(version).isEqualTo("1.1");
    }