static String lastPartOf(String string, String separator) {
        String[] parts = string.split(separator);
        return parts[parts.length - 1];
    }
@Test
    public void lastPartOfTest() {
        assertEquals("us-east1-a", lastPartOf("https://www.googleapis.com/compute/v1/projects/projectId/zones/us-east1-a", "/"));
        assertEquals("", lastPartOf("", ""));
        assertEquals("", lastPartOf("", "/"));
    }