1. Create the training iterator using SequenceRecordReaderDataSetIterator:

DataSetIterator trainDataSetIterator = new SequenceRecordReaderDataSetIterator(trainFeaturesReader,trainLabelsReader,batchSize,numberOfLabels,false, SequenceRecordReaderDataSetIterator.AlignmentMode.ALIGN_END);

2. Create the test iterator using SequenceRecordReaderDataSetIterator:

DataSetIterator testDataSetIterator = new SequenceRecordReaderDataSetIterator(testFeaturesReader,testLabelsReader,batchSize,numberOfLabels,false, SequenceRecordReaderDataSetIterator.AlignmentMode.ALIGN_END);