@Test
  public void isNullOrEmptyTest() {
    assertTrue("String should be declared null", Utils.isNullOrEmpty(null));
    assertTrue("String should be declared empty", Utils.isNullOrEmpty(""));
    assertFalse("String should not be declared empty", Utils.isNullOrEmpty(" "));
    assertFalse("String should not be declared empty", Utils.isNullOrEmpty("a"));
    assertFalse("String should not be declared empty", Utils.isNullOrEmpty(TestUtils.getRandomString(10)));
  }
Tests for {@link Utils#isNullOrEmpty(String)}.
ambry-utils/src/test/java/com/github/ambry/utils/UtilsTest.java