static <E extends @Nullable java.lang.Object> Sets.SetView<E> | 
Sets.difference(java.util.Set<E> set1,
          java.util.Set<?> set2) | 
 Returns an unmodifiable view of the difference of two sets. 
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static <E extends @Nullable java.lang.Object> Sets.SetView<E> | 
Sets.intersection(java.util.Set<E> set1,
            java.util.Set<?> set2) | 
 Returns an unmodifiable view of the intersection of two sets. 
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static <E extends @Nullable java.lang.Object> Sets.SetView<E> | 
Sets.symmetricDifference(java.util.Set<? extends E> set1,
                   java.util.Set<? extends E> set2) | 
 Returns an unmodifiable view of the symmetric difference of two sets. 
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static <E extends @Nullable java.lang.Object> Sets.SetView<E> | 
Sets.union(java.util.Set<? extends E> set1,
     java.util.Set<? extends E> set2) | 
 Returns an unmodifiable view of the union of two sets. 
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