Remove incorrect javadoc regarding "passing the smaller Set first" from Sets.union().
Remove incorrect javadoc regarding "passing the smaller Set first" from Sets.union().

In Sets.intersection() this comment makes sense, since it iterates through set1 as the "main set", and does a contains check against set2 for every element in set1. So iterating through intersection() is O(|set1|) for HashSets, or O(|set1| * log|set2|) for TreeSets. For the union() case though, I don't believe this comment is correct. Iterating through the union involves:

-Iterate through set1. No contains checks are performed. This is simply O(|set1|) (assuming the Set has normal iteration performance)
-Iterate through set2. For every element, a contains check against set1 is performed. Thus we have O(|set2| * C1), where C1 is the cost of a contains() call to set1.

So if set1 is a HashSet we have O(|set1|) + O(|set2|). Order makes no difference. If set1 is a TreeSet we have O(|set1|) + O(|set2| * log|set1|). This is actually *worse* when set1 is the smaller of the two sets.
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