@Override
    public boolean removeAll(final Collection<?> arg) {
        boolean changed = false;
        for (final Object entry : arg) {
            final int i = indexOf(entry);
            if (i >= 0) {
                entries[i] = null;
                changed = true;
            }
        }
        if (changed) {
            clean();
        }
        return changed;
    }
This is an extremely expensive implementation of
{@link Set#removeAll(Collection)}. It is implemented as O(n**2).
vespajlib/src/main/java/com/yahoo/collections/ArraySet.java