Add converters from Pair and Triple to List types.

[donraab]

Signed-off-by: Donald Raab Donald.Raab@bnymellon.com

[mohrezaei]

Philosophical question: shouldn't Twin and Triplet implement unmodifiable list? That would largely obviate this change.

[donraab]

It's a great question @mohrezaei, and Twin and Triplet certainly could implement List or ImmutableList. Unfortunately that would be a heavier lift than the static converter methods, and wouldn't work with Pair or Triple, which is what I was looking for in this particular case. I had some code that used zip which returns a Pair, and I needed to convert it to a List. The types happen to be the same, but unfortunately there isn't a zip that returns Twin. Not sure that would be worth adding.