During a news conference this morning announcing the worst kept secret in the world — his retirement — Johnson offered a look back at an admirable career with his boss, Mayor Lori Lightfoot, at his side. They waved off media questions about his announced exit coming amid an inspector general’s probe of the superintendent being found asleep behind the wheel of his vehicle one late night last month. And there would be no talk, right then and there at least, about who might fill the job, though it’s already the talk of the town.