A lawsuit filed last month by a longtime Cambridge developer could upend the way Massachusetts builds affordable housing. He said he's tried to appeal to city officials about his problems with the affordable housing policy. Most cities demand owners clear a lower bar than Cambridge, requiring between 10 and 15% affordable housing space in new residential buildings. Association of Community Development Corporations, said the policy helps create "much needed" affordable housing options in the state. Just 200 of them were created since 2017, when the city increased the percentage of affordable housing units to 20%.