public void append(final int value) {
        count++;
        var valueToAppend = count * value;
        hashCode = MULTIPLIER * hashCode + (valueToAppend ^ (valueToAppend >>> SHIFT));
        checkSum += valueToAppend;
    }
Recalculates {@link #checkSum} and
{@link #hashCode} using the specified value.

@param value the specified value.
support/cas-server-support-person-directory-core/src/main/java/org/apereo/cas/persondir/cache/HashCodeCalculator.java