Question: An election for the leadership of the Ulster Unionist Party (UUP) was held on 8 April 2017 at the party's Annual General Meeting, the 2017 contested election was triggered after incumbent Leader Mike Nesbitt, elected in 2012, announced following the 2017 assembly election his intention to step down as party leader, the 2017 election to the Northern Ireland Assembly was held on which date?
Sentence (from "Ulster Unionist Party leadership election, 2017"): While initially, Robin Swann and Steve Aiken were expected to run against each other (with candidacies by Doug Beattie, Robbie Butler and Roy Beggs, Jr. also considered possible), in the end only Swann ran and was elected unopposed.
Relevant evidence: No