I've switched to the new Hadoop api (mapreduce) from the old one (mapred). I can't set the number of mappers in the new api. I can use `job.setNumReduceTasks()` to set the number of reducers but there isn't any method for number of mappers. I also tried `conf.setInt("mapred.map.tasks", numMapper)` and `conf.setInt("mapreduce.map.tasks", numMapper)` but it is not working either.