private Collection<Integer> allReducers(HadoopMapReducePlan plan){
  Collection<Integer> res=new HashSet<>();
  for (int i=0; i < plan.reducers(); i++)   res.add(i);
  return res;
}

private Collection < Integer > allReducers ( HadoopMapReducePlan plan ) { Collection < Integer > res = new HashSet < > ( ) ; for ( int i = 0 ; i < plan . reducers ( ) ; i ++ ) res . add ( i ) ; return res ; }
gets all reducers for this job .
