@Test
public void testRtrim() {

  final Object[][] testParameters =
      new Object[][] {{"", ""}, {"hello, world   ", "hello, world"}};
  assertEquals("", StringUtils.rtrim(null));
  for (final Object[] testParameter : testParameters) {
    String expected = (String) testParameter[1];
    String str = (String) testParameter[0];
    assertEquals(expected, StringUtils.rtrim(str));
  }
}