Bug in CrossValidatedMahoutKNNRecommenderEvaluator

[abellogin]

As reported by @afcarvalho1991 in #123:

CrossValidatedMahoutKNNRecommenderEvaluator not working, see Log below.

----------------------------- LOG --------------------------------------

5 [main] INFO org.apache.mahout.cf.taste.impl.model.file.FileDataModel -
Creating FileDataModel for file data/ml-100k/model/train_0.csv
52 [main] INFO org.apache.mahout.cf.taste.impl.model.file.FileDataModel

Reading file info...
Exception in thread "main" java.lang.NumberFormatException: For input
string: ""
at
java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Long.parseLong(Long.java:601)
at java.lang.Long.parseLong(Long.java:631)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.readTimestampFromString(FileDataModel.java:632)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.addTimestamp(FileDataModel.java:595)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.processLine(FileDataModel.java:512)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.processFile(FileDataModel.java:340)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.buildModel(FileDataModel.java:236)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.reload(FileDataModel.java:208)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.(FileDataModel.java:194)
at
org.apache.mahout.cf.taste.impl.model.file.FileDataModel.(FileDataModel.java:149)
at
net.recommenders.rival.examples.movielens100k.CrossValidatedMahoutKNNRecommenderEvaluator.recommend(CrossValidatedMahoutKNNRecommenderEvaluator.java:160)
at
net.recommenders.rival.examples.movielens100k.CrossValidatedMahoutKNNRecommenderEvaluator.main(CrossValidatedMahoutKNNRecommenderEvaluator.java:93)
------------------------------- end-LOG --------------------------------