code: public void fitMultipleFiles(JavaPairRDD<String, String> documentsRdd) {
          /*
              All we want here, is to transform JavaPairRDD into JavaRDD<Sequence<VocabWord>>
           */
          validateConfiguration();
  
          broadcastEnvironment(new JavaSparkContext(documentsRdd.context()));
  
          JavaRDD<Sequence<VocabWord>> sequenceRdd =
                          documentsRdd.map(new KeySequenceConvertFunction(configurationBroadcast));
  
          super.fitSequences(sequenceRdd);
      }
docs: This method builds ParagraphVectors model, expecting JavaPairRDD with key as label, and value as document-in-a-string.
  
  @param documentsRdd