code: public static Pair<Schema, JavaRDD<List<Writable>>> toRecords(DataRowsFacade dataFrame) {
          Schema schema = fromStructType(dataFrame.get().schema());
          return new Pair<>(schema, dataFrame.get().javaRDD().map(new ToRecord(schema)));
      }
docs: Create a compatible schema
  and rdd for datavec
  
  @param dataFrame the dataframe to convert
  @return the converted schema and rdd of writables