1、list到Id唯一确定的map,map的KEY是LeadClient中的ContactId

Map<Long, LeadClient> clientLevelMap = Maps.uniqueIndex(leadClients, new Function<LeadClient, Long>() {
                    public Long apply(LeadClient leadClient) {
                        return leadClient.getContactId();
                    }
                });

2、list到多个id的列表，key也来自LeadClient

ImmutableListMultimap<Long, OrderItem> orderItemMap = Multimaps.index(orderItems, new Function<OrderItem, Long>(){
                public Long apply(OrderItem orderItem){
                    return orderItem.getOrderId();
                }
            });