grommitz

    @Test
    public void mapEachTraderToTheSumOfTheirTransactions() {
        //TODO: Create a Map<String, Integer> that maps each Trader's name with the sum of all its Transactions’ values
        Map<String, Integer> mapNameToSumValue = new HashMap<>();


        mapNameToSumValue =
                transactions.stream()
                        .collect(groupingBy(transaction -> transaction.getTrader().getName(),
                                summingInt(transaction -> transaction.getValue())