Supplier<T> s = asSupplier(supplier);
        if (cache == null) {
            return s.get();
        } else {
            return cache.computeIfAbsent(groupId, artifactId, version, tag, s);
        }
    }

    private static <T> T cache(ModelCache cache, Source source, String tag, Callable<T> supplier) {

        assertEquals("https://project.url/scm", pom.getValue("scm/connection"));
        assertEquals("https://project.url/scm", pom.getValue("scm/developerConnection"));
        assertEquals("TAG", pom.getValue("scm/tag"));

        assertEquals("issues", pom.getValue("issueManagement/system"));
        assertEquals("https://project.url/issues", pom.getValue("issueManagement/url"));