### Question:
CaseInsensitiveComparator implements Comparator<String>, Serializable { @Override public int compare(final String o1, final String o2) { return o1.compareToIgnoreCase(o2); } private  CaseInsensitiveComparator(); static CaseInsensitiveComparator getInstance(); @Override int compare(final String o1, final String o2);  }### Answer:
@Test public void testCompare() { final String testString = "Q6HDKnxquKMn491ZSLy3"; assertThat(comparator.compare(testString, StringUtils.swapCase(testString))).isZero(); }