Question: What was held at the United Center in Chicago, Illinois on June 23-24, 2017 and resulted in Sebastian Aho playing under contract as a prospect of the New York Islanders?
{'answer': '2017 NHL Entry Draft', 'supporting_facts': [['Sebastian Aho (ice hockey, born 1996)', 0], ['Sebastian Aho (ice hockey, born 1996)', 1], ['2017 NHL Entry Draft', 1]]}