SYDNEY — Sydney’s Chinatown in the central city suburb of Haymarket bustles with visitors on a Sunday before the Moon Festival (also known as the Mid-Autumn Festival) that starts in late September, as shoppers come to stock up on mooncakes, Chinese pastries that are enjoyed during the holiday celebrating the harvest. Many people here are also Chinese nationals who immigrated to Australia and have traveled to Australia's most populous city from other places around Australia, during the two-week school holidays period.