Amend: Moved Pair class into uf.common.util to reduce amount of duplicate code
Amend: Added hashCode/equals to Pair
Change-Id: I9a390989f6a7a7ee6618a57d0f50ec681a598dc0
Former-commit-id: ea26d0de84 [formerly ea26d0de84 [formerly eb1dd65cfdcd50b450174a1ca4ef2f2d1e1b9bae]]
Former-commit-id: 126be0cfe5
Former-commit-id: d20958ae92