code: protected Dataset<Sequence> getDataset(SequenceFeaturizer<Annotation> featurizer) {
        Corpus c = Corpus
                      .builder()
                      .corpusType(corpusType)
                      .source(corpus)
                      .format(corpusFormat)
                      .build();
        AnnotatableType[] required = required();
        if (required.length > 0) {
           c = c.annotate(required);
        }
        return c.asSequenceDataSet(new BIOLabelMaker(trainingAnnotation, validTags()), featurizer);
     }
docs: Gets dataset.
  
  @param featurizer the featurizer
  @return the dataset