Flattens the given arrays and keeps each distinct element once, in first-seen order, so several sources combine into
a single list without duplicates. Without a comparator, elements are compared by identity the way a Set does
(SameValueZero) in a single pass; pass equal to merge by a custom relation instead, at the cost of a scan over
the earlier elements for each element.
Combines arrays into their set union.
Flattens the given arrays and keeps each distinct element once, in first-seen order, so several sources combine into a single list without duplicates. Without a comparator, elements are compared by identity the way a
Setdoes (SameValueZero) in a single pass; passequalto merge by a custom relation instead, at the cost of a scan over the earlier elements for each element.