public boolean containsLowerCase(final String lowerSubString) {
        Objects.requireNonNull(lowerSubString);
        if (lowerKey == null) {
            return false;
        }
        return lowerKey.contains(toLowerCase(lowerSubString));
    }
Returns true if the string this {@link CIKey} wraps contains (ignoring case) lowerSubString.
{@code lowerSubString} MUST be all lower case.
<p>
This method is a slight optimisation to avoid having to lower-case the input if it
is know to already be lower-case.
</p>
If lowerSubString is mixed or upper case, use {@link CIKey#containsIgnoreCase(String)} instead.
stroom-util-shared/src/main/java/stroom/util/shared/string/CIKey.java