如何在 Java 中将自定义对象列表重新组合到地图中？

我有以下对象列表

class Account {
    int id;
    String type;
    int balance;
    Customer customer;

    // getters setters
}

class Customer {
    int customerID;
}

List<Account> accounts = new ArrayList<>();
accounts.add(new Account(1, "abc", 17998210, new Customer(190)));
accounts.add(new Account(2, "hsj", 6786179, new Customer(190)));
accounts.add(new Account(4, "ioip", 246179, new Customer(191)));
accounts.add(new Account(4, "ewrew", 90179, new Customer(191)));

我想将上面的转移到 Map 并且键应该是 customerID 并且值应该是 Account 列表

Map<Integer, List<Account>>

Key            Value
190 -> Account(1, "abc", 17998210, 190)
       Account(2, "hsj", 6786179, 190)
191 -> Account(4, "ioip", 246179, 191)
       Account(4, "ewrew", 90179, 191)

如何实现这一目标？