@Test
public void indexOfWithStringArray() {

    Assert.assertEquals(-1, StringUtil.indexOf(null, ""));
    Assert.assertEquals(-1, StringUtil.indexOf(null, null));
    String[] strings = { "a", null };
    Assert.assertEquals(-1, StringUtil.indexOf(strings, ""));
    Assert.assertEquals(-1, StringUtil.indexOf(strings, "b"));
    Assert.assertEquals(0, StringUtil.indexOf(strings, "a"));
    Assert.assertEquals(1, StringUtil.indexOf(strings, null));
}