### Question:
PackageVersionComparator implements Comparator<String> { public static boolean isEquivalent(String theSpec, String thePackageVersion) { String[] o1parts = theSpec.split("\\."); String[] o2parts = thePackageVersion.split("\\."); for (int i = 0; i < o1parts.length; i++ ) { if (!o1parts[i].equals("x")) { if (!o1parts[i].equals(o2parts[i])) { return false; } } } return true; }  @Override int compare(String o1, String o2); static boolean isEquivalent(String theSpec, String thePackageVersion); static final PackageVersionComparator INSTANCE; }### Answer:
@Test public void testIsEquivalent() { assertTrue(PackageVersionComparator.isEquivalent("1.2.x", "1.2.3")); assertTrue(PackageVersionComparator.isEquivalent("1.2", "1.2.3")); assertTrue(PackageVersionComparator.isEquivalent("1.2.3", "1.2.3")); assertFalse(PackageVersionComparator.isEquivalent("1.2.4", "1.2.3")); assertFalse(PackageVersionComparator.isEquivalent("1.3", "1.2.3")); }