The code is taking too files. Modifies the data using several specific modifiers. Merge the data by unique ID and write it to the output file.
NOTE: Originally the code was taking only one file. But i rewrote it to take two files instead. Because overwise it makes no sense to implement Combiner class is it always takes only one iterator. I guess that is the perpose of the implemented algortihm.
There are still places to improve.