The validator used to clear the sealed flag and the children in the validator. But it did not clear the count down latch. This led to a situation where we would throw an IOException from fillChildren because we did have the latch, but it was zero, and the sealed flag was cleared. This simply resets the node every time, which I think is the safest solution as setting the childrenProgress to null in the validator might end poorly if someone was waiting on it. Another solution was to just remove the throw inside fillChildren. This felt like the cleanest solution.
