@Test
void testCheckPackageFriendly() {

    assertTrue(isPackageFriendly("a.b"));
    assertTrue(isPackageFriendly("a"));
    assertTrue(isPackageFriendly("a.b.c"));
    assertFalse(isPackageFriendly("a-b.c"));
    assertFalse(isPackageFriendly("0a.b.c"));
}