Java 集合存在相同属性，其他元素累加

OutpatientPayWayAccountVO vo = new OutpatientPayWayAccountVO();
        vo.setIncomeAmount(new BigDecimal(100));
        vo.setPayName("支付宝");
       
        OutpatientPayWayAccountVO vo1 = new OutpatientPayWayAccountVO();
        vo1.setIncomeAmount(new BigDecimal(0.2));
        vo1.setPayName("微信");
       
        OutpatientPayWayAccountVO vo2 = new OutpatientPayWayAccountVO();
        vo2.setIncomeAmount(new BigDecimal(10));
        vo2.setPayName("现金");        
        List<OutpatientPayWayAccountVO> list1 = new ArrayList<>();
        list1.add(vo);
        list1.add(vo1);
        list1.add(vo2);        
       
        OutpatientPayWayAccountVO vo_1 = new OutpatientPayWayAccountVO();
        vo_1.setIncomeAmount(new BigDecimal(100));
        vo_1.setPayName("支付宝");
       
        OutpatientPayWayAccountVO vo_2 = new OutpatientPayWayAccountVO();
        vo_2.setIncomeAmount(new BigDecimal(10));
        vo_2.setPayName("微信");
       
        OutpatientPayWayAccountVO vo_3 = new OutpatientPayWayAccountVO();
        vo_3.setIncomeAmount(new BigDecimal(0.2));
        vo_3.setPayName("现金");
       
        List<OutpatientPayWayAccountVO> list_2 = new ArrayList<>();
        list_2.add(vo_1);
        list_2.add(vo_2);
        list_2.add(vo_3);
       
        List<OutpatientPayWayAccountVO> list = list1.stream().map(m -> {
            list_2.stream().filter(m2-> m.getPayName().equals(m2.getPayName())).forEach(m2-> {
                m.setIncomeAmount(m.getIncomeAmount().add(m2.getIncomeAmount()));
                //m.put("incomeAmount",m2.getIncomeAmount().toString());
                //m.put("age",m2.get("age"));
            });
            return m;
        }).collect(Collectors.toList());
        System.err.println("list:" + list);