public void testTrimToNull() {
   assertEquals(FOO, StringUtils.trimToNull(FOO + "  "));
   assertEquals(FOO, StringUtils.trimToNull(" " + FOO + "  "));
   assertEquals(FOO, StringUtils.trimToNull(" " + FOO));
   assertEquals(FOO, StringUtils.trimToNull(FOO + ""));
   assertEquals(null, StringUtils.trimToNull(" \t\r\n\b "));
   assertEquals(null, StringUtils.trimToNull(StringUtilsTest.TRIMMABLE));
   assertEquals(
       StringUtilsTest.NON_TRIMMABLE, StringUtils.trimToNull(StringUtilsTest.NON_TRIMMABLE));
   assertEquals(null, StringUtils.trimToNull(""));
   assertEquals(null, StringUtils.trimToNull(null));
 }
 public void testTrimToNull() {
   assertNull(StringUtils.trimToNull(null));
   assertNull(StringUtils.trimToNull(""));
   assertNull(StringUtils.trimToNull(" "));
   assertNull(StringUtils.trimToNull("    "));
   assertNotNull(StringUtils.trimToNull("aa"));
   assertNotNull(StringUtils.trimToNull("  aa  "));
 }