Question:  In what international contest did Howard David Jr. defeat the undisputed heavyweight boxing champion of 1978?

Context paragraphs:
Superman vs. Muhammad Ali: Superman vs. Muhammad Ali is an oversize celebrity comics comic book published by DC Comics in 1978.  The 72-page book features Superman teaming up with the heavyweight boxing champion Muhammad Ali to defeat an alien invasion of Earth.  It was based on an original story by Dennis O'Neil which was adapted by Neal Adams, with pencils by Adams, and figure inks by Dick Giordano with background inks by Terry Austin.

Leon Spinks: Leon Spinks (born July 11, 1953) is an American former professional boxer who competed from 1977 to 1995.  In only his eighth professional fight, he won the undisputed heavyweight championship in 1978 after defeating Muhammad Ali via split decision, in what was considered one of the biggest upsets in boxing history.  Spinks was later stripped of the WBC title for facing Ali in an unapproved rematch seven months later, which he lost by unanimous decision.

Bob Martin (boxer): 'Fighting' Bob Martin (November 11, 1897 – 1978) was a heavyweight boxing champion who became the Heavyweight Champion of the American Expeditionary Forces

Bare Knuckle Boxing Hall of Fame: The Bare Knuckle Boxing Hall of Fame is a museum and hall of fame in Belfast, New York, dedicated to the sport of bare-knuckle boxing.  It is housed in barns that were once owned by the Greco-Roman wrestling champion and physical culture pioneer William Muldoon.  The heavyweight boxing champion John L. Sullivan, who fought in both bare-knuckled and gloved boxing contests, trained in these barns under Muldoon's guidance for his championship bout against Jake Kilrain in 1889.  The barns were originally across Main Street from their current location, on the grounds of the Belfast United Methodist Church.  They were bought, moved, and restored by Scott Burt when the church became no longer interested in maintaining them.  Burt opened the Hall of Fame in 2009, when it had its first induction class.

Philadelphia Jack O'Brien: Joseph Francis Hagan (better known as Philadelphia Jack O'Brien) (January 17, 1878 – November 12, 1942) was the world light heavyweight boxing champion.  Nat Fleischer, founder and editor of "The Ring" Magazine, ranked O'Brien as the No. 2 All-Time Light Heavyweight, and famed boxing promoter Charley Rose ranked him as the No. 3 All-Time Light Heavyweight.  O'Brien was inducted into the Ring Magazine hall of fame in 1968, the World Boxing Hall of Fame in 1987, and the International Boxing Hall of Fame in 1994.

Frank Goddard: Percy Frank Goddard (27 November 1891- 8 December 1957) was a British boxer who became the heavyweight boxing champion in 1923.  Goddard's career begin in 1914 and it soon became apparent that he was one of the best boxers in the UK.  He became the British heavyweight boxing champion on 26 May 1919 having beaten Jack Curphey for the vacant British Boxing Board of Control (BBBofC) British heavyweight title.  Goddard lost the British heavyweight championship on 17 June 1919 to Joe Beckett.

UCW-Zero Heavyweight Championship: The UCW-Zero Heavyweight Championship is the primary singles championship title in Ultra Championship Wrestling-Zero.  It was first won by Blitz Mason in March 2003 and defended throughout the state of Utah, most often Salt Lake City, Utah, but also in the Rocky Mountains and the Southwest United States.  The title was formerly recognized by AWA Superstars from 2005 to 2007, and then by the National Wrestling Alliance when the promotion became an NWA territory that same year.  On February 26, 2011, the UCW-Zero Heavyweight Championship was around the waist of Los Mochis Paco until it was stolen by Tyler Cintron after Junior X attacked Paco.  Later, Paco retrieved his belt back from Tyler Cintron.  The following show however, Tyler Cintron walks into the ring with his own UCW-Zero Heavyweight Championship.  UCW Director Blitz decide to make a Triple Threat TLC Match to determine the Undisputed UCW-Zero Heavyweight Champion which took place on June 4, 2011.  Los Mochis Paco was the victor to become the Undisputed Heavyweight Champion.  It would however be short lived because Los Mochis Paco was attacked by Black Out in the back and broke his leg and was unable to defend it.  Two Weeks later on June 18, 2011, Director for the night and Former 4 time UCW-Zero Heavyweight Champion Martin Casaus made a Gauntlet Match to determine a New Champion.  In the end, it was Junior X that prevailed and became the NEW UCW-Zero Heavyweight Champion.  2011 Rocky Mountain Rumble Champion Kid Kade went on to win the UCW-Zero Heavyweight Champion after defeating Junior X at "Meltdown Mayhem" on August 13, 2011.

Jack Johnson (boxer): John Arthur "Jack" Johnson (March 31, 1878 – June 10, 1946), nicknamed the Galveston Giant, was an American boxer, who—at the height of the Jim Crow era—became the first African American world heavyweight boxing champion (1908–1915).  Johnson went on to become one of the most dominant champions of his time, and remains a significant historical figure in heavyweight boxing history, with his 1910 fight against James J. Jeffries being dubbed the "fight of the century."  Johnson was faced with much controversy when he was charged with violating the Mann Act in 1912, even though there was an obvious lack of evidence and the charge was largely racially based.  In a documentary about his life, Ken Burns notes that "for more than thirteen years, Jack Johnson was the most famous and the most notorious African-American on Earth".

Howard Davis Jr.: Howard Edward Davis Jr. (February 14, 1956 – December 30, 2015) was an American amateur and professional boxer.  Growing up on Long Island as the eldest of 10 children, Davis first learned boxing from his father.  After being inspired by a movie about Muhammad Ali, Davis embarked on his amateur career.  He won the 1976 Olympic gold medal one week after his mother died.  He was also awarded the Val Barker Trophy at the Olympics, beating out such boxers as Sugar Ray Leonard, Michael Spinks and Leon Spinks.

Tommy Burns (boxer): Tommy Burns (June 17, 1881May 10, 1955), born Noah Brusso, is the only Canadian-born World Heavyweight Boxing Champion.  The first to travel the globe in defending his title, Tommy made 11 title defences despite often being the underdog due to his size.  Burns famously challenged all comers as Heavyweight Champion, leading to a celebrated bout with the American Jack Johnson.  According to his biographer, Burns insisted, "I will defend my title against all comers, none barred.  By this I mean white, black, Mexican, Indian, or any other nationality.  I propose to be the champion of the world, not the white, or the Canadian, or the American.  If I am not the best man in the heavyweight division, I don't want the title."

Supporting paragraphs: Howard Davis Jr. Leon Spinks
Answer: the Olympics