Map<Tuple2<String, String>, AbstractMap.SimpleEntry<Double, Double>> grouped = lineitem.stream().filter(Lineitem.L_SHIPDATE.lessOrEqual(sqlDate))
    .collect(groupingBy(t->Tuples.of(t.getLReturnflag().toString(), t.getLLinestatus()), Collectors.collectingAndThen(Collectors.toList(),
                                list-> {double first =
                                        list
                                                .stream()
                                                .mapToDouble(t -> t.getLExtendedprice().doubleValue() * (1 - t.getLDiscount().doubleValue())*(1+t.getLTax().doubleValue())).sum();
                                    double second =
                                            list
                                                    .stream()
                                                    .collect(averagingDouble(t->t.getLTax().doubleValue()));

                                    return new AbstractMap.SimpleEntry<>(first, second);})
                ));

[ERROR] /home/ubuntu/example-parent/src/main/java/com/speedment/example/App.java:[62,126] cannot find symbol
  symbol:   method doubleValue()
  location: class java.util.Optional<java.math.BigDecimal>