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?

Context articles: List of New York Islanders players
2017 NHL Entry Draft
Joel Rechlicz
Prospect Heights, Brooklyn
Christopher Gibson
Alex Anthony
Sebastian Aho (ice hockey, born 1996)
Pittsburgh Penguins–New York Islanders brawl
Live in Chicago 12.19.98 at the United Center
1984 Stanley Cup Finals

The New York Islanders are a professional ice hockey team based in Brooklyn, New York, United States.
 They are members of the Metropolitan Division of the National Hockey League's (NHL) Eastern Conference.
 The Islanders franchise has been a part of the NHL since their inception in 1972, formerly playing their home games at Nassau Veterans Memorial Coliseum.
 The Islanders now play at the Barclays Center.
 Nearly 500 players have played for the team for at least one regular season or playoff game, and nearly 20 have had multiple stints over the years.
The 2017 NHL Entry Draft was the 55th NHL Entry Draft.
 The draft was held from June 23–24, 2017, at the United Center in Chicago, Illinois.
 The first three selections were Nico Hischier, Nolan Patrick and Miro Heiskanen.
Joel Rechlicz (born June 14, 1987) is an American professional ice hockey player currently an unrestricted free agent who most recently played under contract with the Bakersfield Condors of the American Hockey League (AHL).
 Rechlicz is well known for playing the enforcer role and is billed as a tough as nails type of player.
 By signing a three-year entry level contract with the New York Islanders in May 2008, Rechlicz became the first player from the reestablished but now defunct International Hockey League to play a game in the National Hockey League.
 Along with the Islanders, he has also played with the Washington Capitals.
Prospect Heights is a neighborhood in the northwest of the New York City borough of Brooklyn.
 The traditional boundaries are Flatbush Avenue to the west, Atlantic Avenue to the north, Eastern Parkway – beginning at Grand Army Plaza – to the south, and Washington Avenue to the east.
 In the northern section of Prospect Heights are the Vanderbilt Rail Yards, built over as part of the Pacific Park (formerly Atlantic Yards) project.
 The Barclays Center, home to the NBA's Brooklyn Nets basketball team and the NHL's New York Islanders ice hockey team, is located in the northwestern corner of the neighborhood in Pacific Park at Flatbush and Atlantic Avenues.
Christopher Gibson (born 27 December 1992) is a Finnish ice hockey goaltender.
 He is currently playing for the Bridgeport Sound Tigers in the American Hockey League (AHL) as a prospect for the New York Islanders of the National Hockey League (NHL).
 Gibson was selected by the Los Angeles Kings in the 2nd round (49th overall) of the 2011 NHL Entry Draft, although he never played for them, instead signing with the Toronto Maple Leafs, playing in their minor league system before a trade sent Gibson to the Islanders.
 Gibson made his first-ever NHL start for the Islanders on 5 April 2016 against the Washington Capitals.
Alex Anthony is best known as the Public Address announcer for Major League Baseball's New York Mets, a position he has held since 2004, first at Shea Stadium and then at Citi Field since the Mets moved there in 2009.
 He has been called the "Voice of the Mets."
 He also announced New York Jets games at Giants Stadium and New Meadowlands Stadium from 2002-2008, New York Islanders games at the Nassau Coliseum from 1995-1998, backup PA announcer for the New York Rangers 2008-2012 and currently backup PA for the New York Islanders.
 He is currently one of two game day PA announcers for the New York Jets.
 He was the announcer for the US Open Tennis Championship in 2002 and 2003.
Sebastian Aho (born 17 February 1996) is a Swedish professional ice hockey defenceman who is currently playing under contract as a prospect of the New York Islanders in the National Hockey League (NHL).
 Aho was drafted by the Islanders, 139th overall, in the 2017 NHL Entry Draft.
The Penguins–Islanders brawl was a National Hockey League (NHL) regular season ice hockey game between the Pittsburgh Penguins and the New York Islanders that resulted in a record for combined penalty minutes for both teams.
 The game was played on February 11, 2011, at Nassau Veterans Memorial Coliseum, the home arena of the Islanders at the time.
 New York won the game 9–3.
 In all, 65 penalties were assessed, including 15 fighting majors and 21 game misconducts, resulting in a total of 346 penalty minutes.
Live in Chicago 12.19.98 at the United Center, also known as simply Live in Chicago 12.19.98, is a live album by the Dave Matthews Band, released by RCA on October 23, 2001.
 It was recorded at the United Center in Chicago, Illinois.
 It was originally broadcast as a live webcast, with the recording released on CD.
The 1984 Stanley Cup Final was held between the Edmonton Oilers and the then-defending champion New York Islanders.
 The Islanders had swept the Oilers in four straight games to win the Cup.
 In 1984, the Islanders were seeking their fifth consecutive Stanley Cup championship, but the upstart Oilers would win the best-of-seven series four games to one to win their first Stanley Cup, becoming the third post-1967 expansion team and first former World Hockey Association team to win the Cup, and also the first team based west of Chicago to win the Cup since the WCHL's Victoria Cougars became the last non-NHL team to win it in .
 It was also the fifth straight Finals of teams that joined the NHL in 1967 or later and a rematch of the 1983 Finals—a Stanley Cup Finals rematch would not happen again until the Finals.
 s of 2017 , the Islanders' four consecutive Cup wins (, , , 1983) and their appearance in the 1984 Cup Finals is an NHL record of 19 consecutive playoff series wins that currently stands unbroken.
 This would be the second of eight consecutive Finals contested by a team from Alberta (the Oilers appeared in six, the Calgary Flames in two), and the first of five consecutive Finals to end with the Cup presentation on Alberta ice (the Oilers won four times, the Montreal Canadiens one).