* modifications, or we'll modify the already-built ImmutableMultiset.
     */
    boolean buildInvoked = false;
    /**
     * In the event of a setCount(elem, 0) call, we may need to remove elements, which destroys the
     * insertion order property of ObjectCountHashMap. In that event, we need to convert to a
     * ObjectCountLinkedHashMap, but we need to know we did that so we can convert back.
     */