The Group of 20 summit in South Africa has ended with the glaring absence of the United States — the next country to lead the bloc. The Trump administration boycotted the two days of talks involving leaders of the world’s richest and top developing economies. South African President Cyril Ramaphosa declared the summit in Johannesburg closed Sunday by banging a wooden gavel on a block like a judge would, in a G20 tradition. The gavel would normally be handed over to the leader of the next country to hold the rotating presidency, but no U.S. official was there to receive it.