@Override
    public void copyFrom(final CriteriaSet<T> other) {
        this.set.clear();
        this.set.addAll(other.set);
        this.matchNull = other.matchNull;
        this.matchAll = other.matchAll;
    }
By default the criteria will match anything. NULL matchAll implies match
anything when nothing is in the set or we are to not matchNull. By
setting match all it will match all regardless.
stroom-legacy/stroom-legacy-model_6_1/src/main/java/stroom/legacy/model_6_1/CriteriaSet.java