public boolean containsIgnoreCase(final String subString) {
        Objects.requireNonNull(subString);
        if (lowerKey == null) {
            return false;
        }
        return lowerKey.contains(toLowerCase(subString));
    }
Returns true if the string this {@link CIKey} wraps contains subString
ignoring case.
If subString is all lower case, use {@link CIKey#containsLowerCase(String)} instead.
stroom-util-shared/src/main/java/stroom/util/shared/string/CIKey.java