Chinese President Xi Jinping, Brunei's Sultan Hassanal Bolkiah and Brunei's Crown Prince Al-Muhtadee Billah attend a luncheon at the Nurul Iman Palace in Bandar Seri Begawan, Brunei, November 19, 2018. REUTERS/Ahim Rani 

Brunei's Crown Prince Al-Muhtadee Billah salutes during his father's 69th birthday celebrations in Bandar Seri Begawan, Brunei August 15, 2015. Brunei's Sultan Hassanal Bolkiah was born on July 15, 1946. The official birthday celebrations were postponed due to the Sultan's birthday falling in the month of Ramadan, according to local media. REUTERS/Ahim Rani

Brunei's Sultan Hassanal Bolkiah (centre R) and Crown Prince Al-Muhtadee Billah (centre L) shake hands with worshippers as they leave the Jame'Asr Hassanil Bolkiah state mosque, after State Prayers asking for the protection and security of Palestine and its people, in Bandar Seri Begawan July 14, 2014. REUTERS/Ahim Rani (BRUNEI - Tags: RELIGION POLITICS) 

Brunei’s Crown Prince Al-Muhtadee Billah (C) shakes hands with Malaysian ministers during the welcoming ceremony outside the office of Malaysia's Prime Minister Najib Razak (rear) in Putrajaya, near Kuala Lumpur November 12, 2013. REUTERS/Samsul Said (MALAYSIA - Tags: ROYALS POLITICS) 

Brunei’s Crown Prince Al-Muhtadee Billah (L) and Malaysia's Prime Minister Najib Razak (top) walk down a stage during a welcoming ceremony in Putrajaya, outside Kuala Lumpur November 12, 2013. REUTERS/Samsul Said (MALAYSIA - Tags: ROYALS POLITICS) 

Brunei’s Crown Prince Al-Muhtadee Billah inspects an honour guard during the state welcoming ceremony outside the office of Malaysia's Prime Minister Najib Razak (not pictured), in Putrajaya, near Kuala Lumpur November 12, 2013. REUTERS/Samsul Said (MALAYSIA - Tags: POLITICS ROYALS) 

Prince Haji Al-muhtadee Billah, Crown Prince of Brunei, addresses the 68th session of the United Nations General Assembly at UN headquarters in New York, September 28, 2013. REUTERS/Ray Stubblebine (UNITED STATES - Tags: POLITICS ROYALS) 

Brunei’s Crown Prince Al-Muhtadee Billah looks on during the celebrations of his father’s 67th birthday in Bandar Seri Begawan September 15, 2013. Brunei’s Sultan Hassanal Bolkiah was born on July 15, 1946. The official birthday celebrations were postponed to September 15 due to the Sultan's birthday falling in the month of Ramadan, according to local media. REUTERS/Ahim Rani (BRUNEI - Tags: ROYALS ANNIVERSARY) 

Brunei's Crown Prince Haji Al-Muhtadee Billah (L) and his wife Pengiran Anak Sarah arrive at a gala dinner organised on the eve of the abdication of Queen Beatrix of the Netherlands and the inauguration of her successor King Willem-Alexander at the Rijksmuseum in Amsterdam April 29, 2013. REUTERS/Robin Utrecht/Pool (NETHERLANDS - Tags: ROYALS POLITICS ENTERTAINMENT)

Brunei's Crown Prince Haji Al-Muhtadee Billah (L) and his wife Pengiran Anak Sarah arrive at a gala dinner organised on the eve of the abdication of Queen Beatrix of the Netherlands and the inauguration of her successor King Willem-Alexander at the Rijksmuseum in Amsterdam April 29, 2013. REUTERS/Toussaint Kluiters (NETHERLANDS - Tags: ROYALS POLITICS ENTERTAINMENT)

Brunei's Crown Prince Haji Al-Muhtadee Billah (L) and his wife Pengiran Anak Sarah arrive at a gala dinner organised on the eve of the abdication of Queen Beatrix of the Netherlands and the inauguration of her successor King Willem-Alexander at the Rijksmuseum in Amsterdam April 29, 2013. REUTERS/Toussaint Kluiters (NETHERLANDS - Tags: ROYALS POLITICS ENTERTAINMENT)

Brunei's Crown Prince Al-Muhtadee Billah addresses the 67th United Nations General Assembly at the U.N. Headquarters in New York, September 27, 2012. REUTERS/Lucas Jackson (UNITED STATES - Tags: POLITICS) 

Brunei's Crown Prince Al-Muhtadee Billah addresses the 66th United Nations General Assembly at the U.N. headquarters in New York September 26, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: POLITICS ROYALS) 

Brunei's Crown Prince Al-Muhtadee Billah addresses the 66th United Nations General Assembly at the U.N. headquarters in New York September 26, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: POLITICS ROYALS) 

Visiting Indonesian President Susilo Bambang Yudhoyono (R) talks to Brunei?s Sultan Hassanal Bolkiah (2nd L) and Brunei's Crown Prince Al-Muhtadee Billah at Nurul Iman Palace in Bandar Seri Begawan February 24, 2011. Yudhoyono is on a two-day state visit to Brunei. REUTERS/Ahim Rani (BRUNEI - Tags: POLITICS ROYALS) 

Brunei's Sultan Hassanal Bolkiah (C) talks to his eldest son Crown Prince Al-Muhtadee Billah (L), as they walk with his youngest brother Prince Jefri (R), at the head of the Maulidur Rasul parade in Bandar Seri Begawan February 15, 2011. Muslims throughout Brunei on Tuesday commemorated Maulidur Rasul, also known as Mawlid or Maulud Nabi, the birthday of Prophet Muhammad. REUTERS/Ahim Rani (BRUNEI DARUSSALAM - Tags: SOCIETY RELIGION ROYALS POLITICS) 

Brunei's Sultan Hassanal Bolkiah (C), walks with his youngest brother Prince Jefri (R) and his eldest son Crown Prince Al-Muhtadee Billah (front L), as he leads the Maulidur Rasul parade in Bandar Seri Begawan February 15, 2011. Muslims throughout Brunei on Tuesday commemorated Maulidur Rasul, also known as Mawlid or Maulud Nabi, the birthday of Prophet Muhammad. REUTERS/Ahim Rani (BRUNEI DARUSSALAM - Tags: SOCIETY RELIGION POLITICS ROYALS) 

Brunei?s Sultan Hassanal Bolkiah (2nd R) stands with his sons Prince Abdul Azim (L) and Crown Prince Al-Muhtadee Billah, and his brother Prince Sufri (R), as they recite a prayer during a thanksgiving marking his 64th birthday at a mosque in Bandar Seri Begawan July 14, 2010. Hassanal was born July 15, 1946 in Brunei Town, now known as Bandar Seri Begawan, and ascended to the throne to become the 29th Sultan of Brunei on October 5, 1967. REUTERS/Ahim Rani (BRUNEI - Tags: ROYALS IMAGES OF THE DAY) 

The Crown Prince of Brunei Haji Al-Muhtadee Billah arrives at the opening ceremony of the Commonwealth Heads of Government Meeting in Port-Of-Spain November 27, 2009. REUTERS/Carlos Barria (TRINIDAD AND TOBAGO POLITICS ROYALS) 

Golfer Rick Kulacz (L) of Australia receives the Brunei Open 2008 trophy from Brunei's Crown Prince Al-Muhtadee Billah in Bandar Seri Begawan August 24, 2008.REUTERS/Ahim Rani (BRUNEI) 

Brunei's Crown Prince Al-Muhtadee Billah salutes the royal guard of honour during his father's 62nd birthday celebration in Bandar Seri Begawan July 15, 2008. REUTERS/Ahim Rani (BRUNEI) 

Brunei's Crown Prince Al-Muhtadee Billah (C) shares a light moment with his uncles Prince Sufri (L) and Prince Mohammed after his father's birthday celebration in Bandar Seri Begawan July 15, 2008. REUTERS/Bazuki Muhammad (BRUNEI) 

Brunei's Crown Prince Al-Muhtadee Billah sits during his father's birthday celebration in Bandar Seri Begawan July 15, 2008. REUTERS/Bazuki Muhammad (BRUNEI) 

Brunei's royal family, Sultan Hassanal Bolkiah (2nd R), Queen Saleha (2nd L), his second wife Azrinaz (R), Crown Prince Al-Muhtadee Billah (3rd L) and Princess Sarah, leave the Sultan's 62nd birthday celebration at Nurul Iman Palace in Bandar Seri Begawan July 15, 2008.
REUTERS/Bazuki Muhammad (BRUNEI) 

Brunei's Crown Prince Al-Muhtadee Billah and Princess Sarah leave Sultan Hassanal Bolkiah's 62nd birthday celebration at Nurul Iman Palace in Bandar Seri Begawan July 15, 2008.
REUTERS/Bazuki Muhammad (BRUNEI) 

Brunei's Sultan Hassanal Bolkiah (C), followed by crown prince Al-Muhtadee Billah, is greeted
after a prayer at a mosque in Bandar Seri Begawan July 14, 2008. Hassanal Bolkiah on Tuesday celebrates his 62nd birthday. REUTERS/Ahim Rani (BRUNEI) 

Brunei's Sultan Hassanal Bolkiah (R) walks with Malaysian Prime Minister Abdullah Ahmad Badawi at a recreational park in Bandar Seri Begawan August 14, 2007. Malaysia and Brunei have made good progress on resolving a sea boundary dispute that has held up oil exploration for four years and only need to sort out some details, Malaysia's prime minister said on Tuesday. With them are Brunei's Crown Prince Al-Muhtadee Billah (2nd L) and Malaysian Foreign Minister Syed Hamid. REUTERS/Ahim Rani (Brunei Darussalam) 

Haji Al-Muhtadee Billah, Crown Prince of Brunei, smiles as he meets German Foreign Minister Frank-Walter Steinmeier in Berlin June 13, 2006. REUTERS/Alexandra Beckstein (GERMANY) 

Vietnam's Prime Minister Phan Van Khai (L) and Brunei's Crown Prince Haji Al-Muhtadee Billah walk into a meeting room at the Government Office in Hanoi March 21, 2006. Brunei's Crown Prince Billah is on a three-day visit to Vietnam to strengthen ties between the two countries. REUTERS/Kham 

Vietnam's President Tran Duc Luong (R) talks with Brunei's Crown Prince Haji Al-Muhtadee Billah at the Presidential Palace in Hanoi March 21, 2006. Brunei's Crown Prince Billah is on a three-day visit to Vietnam to strengthen ties between the two countries. REUTERS/Kham 

Ha Van Hien (R), the husband of Vietnam's Vice President Truong My Hoa shakes hands with Pengiran Anak Sarah, the wife of Brunei's Crown Prince Haji Al-Muhtadee Billah, at the Presidential Palace after a welcoming ceremony in Hanoi March 20, 2006. REUTERS/Kham 

Ha Van Hien (R), the husband of Vietnam's Vice President Truong My Hoa and Pengiran Anak Sarah (L), Brunei's Crown Prince Haji Al-Muhtadee Billah's wife leave the Presidential Palace after a welcoming ceremony in Hanoi March 20, 2006. REUTERS/Kham 

Pengiran Anak Sarah (R), the wife of Brunei's Crown Prince Haji Al-Muhtadee Billahe leaves the Presidential Palace after a welcoming ceremony in Hanoi March 20, 2006. REUTERS/Kham 

Brunei's Crown Prince Haji Al-Muhtadee Billah (R) and his wife Pengiran Anak Sarah pose for a photo at the Presidential Palace in Hanoi March 20, 2006. REUTERS/Kham 

Vietnam's Vice President Truong My Hoa (2nd R), her husband Ha Van Hien (R), Brunei's Crown Prince Haji Al-Muhtadee Billah (2nd L) and his wife Pengiran Anak Sarah pose for a photo in front of the statue of Vietnamese late revolutionary leader Ho Chi Minh at the Presidential Palace in Hanoi March 20, 2006. Brunei's royal couple are in Hanoi as part of three-day visit to Vietnam to strengthen ties between the two countries. REUTERS/Kham 

Vietnam's Vice President Truong My Hoa (R) and Brunei's Crown Prince Haji Al-Muhtadee Billah pose for a photo in front of a statue Vietnamese late revolutionary leader Ho Chi Minh during a welcoming ceremony at the Presidential Palace in Hanoi March 20, 2006. REUTERS/Kham 

Crown Prince Naruhito of Japan, smiles upon his arrival at the Togu Palace in Tokyo, 11 September, 2004. [He returned from Brunei after attending the wedding ceremony of Brunei Crown Prince Al-Muhtadee Billah Bolkiah. His secluded wife Crown Princess Masako missed a second successive foreign trip because of a stress-induced disorder.] 

Crown Prince Naruhito of Japan, smiles upon his arrival at the Togu Palace in Tokyo, 11 September, 2004. He returned from Brunei after attending the wedding ceremony of Brunei Crown Prince Al-Muhtadee Billah Bolkiah. His secluded wife Crown Princess Masako missed a second successive foreign trip because of a stress-induced disorder. REUTERS/Yoshikazu Tsuno/POOL 

Britain's Duke of Gloucester and Japan's Crown Prince Naruhito arrive for the Brunei's crown prince royal wedding banquet in Bandar Seri Begawan. Britain's Duke of Gloucester (L) and Japan's Crown Prince Naruhito arrive for Brunei's crown prince's royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan on September 10, 2004. The royals are in the capital of the oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. Picture taken September 10, 2004. REUTERS/Ahmad Yusni/Pool 

Brunei's Sultan Hassanal Bolkiah, Philippines Gloria Macapagal Arroyo and Malaysia's King Syed Sirajuddin recite a prayer during the royal wedding banquet in Bandar Seri Begawan. Brunei's Sultan Hassanal Bolkiah (C), Philippines Gloria Macapagal Arroyo (R) and Malaysia's King Syed Sirajuddin recite a prayer during the royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan, September 10, 2004. The royal guests and the leader are in the capital of the oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Ahmad Yusni/Pool 

Philippine President Gloria Macapagal Arroyo and royals arrive for the Brunei crown prince wedding banquet at Nurul Iman Palace in Bandar Seri Begawan. Philippine President Gloria Macapagal Arroyo (R), Brunei's Queen Saleha (C) and Malaysia's Queen Fauziah arrive for the Brunei crown prince wedding banquet at Nurul Iman Palace in Bandar Seri Begawan, September 10, 2004. The royal guests and the leader are in the capital of the oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Ahmad Yusni/Pool 

Former Malaysian prime minister Mahathir Mohamad talks to an unidentified guest as Singapore's Minister Mentor Lee Kuan Yew reads during the royal wedding banquet in Bandar Seri Begawan. Former Malaysian prime minister Mahathir Mohamad (L) talks to an unidentified guest as Singapore's Minister Mentor Lee Kuan Yew reads during the royal wedding banquet at the Nurul Iman Palace in Bandar Seri Begawan on September 10, 2004. Mahathir and Lee are in the capital of oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Andy Wong/Pool 

Malaysia's King Syed Sirajuddin and Philippine President Gloria Macapagal Arroyo smile as they arrive at the Brunei's crown prince wedding banquet in Bandar Seri Begawan. Malaysia's King Syed Sirajuddin (L) and Philippine President Gloria Macapagal Arroyo smile as they arrive at the Brunei's crown prince wedding banquet at the Nurul Iman Palace in Bandar Seri Begawan on September 10, 2004. Sirajuddin and Arroyo are in the capital of the oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Andy Wong/Pool 

Bahrain's King Sheikh Hamad Isa Al-Khalifa talks during the Brunei's crown prince wedding banquet in Bandar Seri Begawan. Bahrain's King Sheikh Hamad Isa Al-Khalifa (2nd L) talks to Brunei's Queen Saleha (L) as Brunei's Crown Prince Al-Muhtadee Billah Bolkiah (2nd L) and his wife Sarah Pengiran Salleh during the crown prince wedding banquet at the Nurul Iman Palace in Bandar Seri Begawan on September 10, 2004. REUTERS/Andy Wong/Pool 

Britain's Duke of Gloucester Prince Richard and Japan's Crown Prince Naruhito arrive for the Brunei's crown prince royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan. Britain's Duke of Gloucester Prince Richard (L) and Japan's Crown Prince Naruhito arrive for the Brunei's crown prince royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan on September 10, 2004. The royals are in the capital of the oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Andy Wong/Pool 

Brunei's Sultan Hassanal Bolkiah (C) arrives for the crown prince wedding banquet with other royalty at Nurul Iman Palace in Bandar Seri Begawan, September 10, 2004. The royal guest and the leader are in the capital of oil-rich Brunei to attend the wedding ceremony of Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh. REUTERS/Ahmad Yusni/Pool BM/dbp 

Brunei's Sarah Pengiran Salleh arrives for her wedding ceremony to marry [Crown Prince Al-Muhtadee Billah] at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Under heavy rain Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh drive through central Bandar Seri Begawan in a golden Rolls Royce following their wedding ceremony on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty.??? USE ONLY 

Brunei's Sarah Pengiran Salleh follows her husband, Brunei's Crown Prince Al-Muhtadee Billah, after their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Newly-wed royal couple, Brunei's Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh recite a prayer during their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Japanese Crown Prince Naruhito (L) speaks to Brunei's Sultan Hassanal Bolkiah at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. Naruhito is in the capital of oil-rich Brunei to attend the wedding ceremony of Brunei's [Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh.] 

Brunei's Crown Prince Al-Muhtadee Billah (R) kisses his mother Queen Saleha's hand as his wife Sarah Pengiran Salleh kisses his father's hand, Sultan Hassanal Bolkiah, after their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Newly-wed royal couple, Brunei Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh, recite a prayer during their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Brunei's Crown Prince Al-Muhtadee Billah blesses wife Sarah Pengiran Salleh as his father Sultan Hassanal Bolkiah (R) looks on during their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Brunei's Sarah Pengiran Salleh holds her husband Crown Prince Al-Muhtadee Billah as they walk down the aisle after their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Brunei's Sultan Hassanal Bolkiah sit during the wedding ceremony of his son [Crown Prince Al-Muhtadee Billah and Sarah Pengiran Salleh] at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. 

Brunei's Sarah Pengiran Salleh arrives for her wedding ceremony with [Crown Prince Al-Muhtadee Billah] at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. ??? USE ONLY 

Newlywed royal couple, Brunei's Crown Prince Al-Muhtadee Billah (L) and Sarah Pengiran Salleh leave their wedding ceremony at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. ??? USE ONLY 

Brunei's Crown Prince Al-Muhtadee Billah Bolkiah and wife Sarah Pengiran Salleh arrive for the royal wedding banquet in Bandar Seri Begawan. Brunei's Crown Prince Al-Muhtadee Billah Bolkiah and wife Sarah Pengiran Salleh arrive for the royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. REUTERS/Andy Wong/Pool 

Brunei's Crown Prince Al-Muhtadee Billah Bolkiah and wife Sarah Pengiran Salleh arrive for the royal wedding banquet in Bandar Seri Begawan. Brunei's Crown Prince Al-Muhtadee Billah Bolkiah and wife Sarah Pengiran Salleh arrive for the royal wedding banquet at Nurul Iman Palace in Bandar Seri Begawan on September 9, 2004. The future king of oil-rich Brunei presented his new teenage bride to the world on Thursday in a gilded, traditional ceremony attended by Asian leaders and Arab royalty. REUTERS/Andy Wong/Pool