Beijing (AFP) – China’s troubled property sector suffered another blow this month when frustrated homebuyers stopped making mortgage payments on units in unfinished projects. The boycott came with many developers struggling to manage mountains of debt, and fears swirling that the crisis could spread to the rest of the Chinese — and global — economy. How big is China’s property sector? Colossal. Property and related industries are estimated to contribute as much as a quarter of China’s Gross Domestic Product (GDP). The sector took off after market reforms in 1998. There was a breathtaking con…