Java - 이중 중괄호와 Anti-Pattern

1Map<String, Object> map = new HashMap<>();
2map.put("customerId", customer.getCustomerId().toString().getBytes());
3map.put("name", customer.getName());
4map.put("email", customer.getEmail());
5map.put("createdAt", Timestamp.valueOf(customer.getCreatedAt()));
6return map;

1return new HashMap<>() {{
2    put("customerId", customer.getCustomerId().toString().getBytes());
3    put("name", customer.getName());
4    put("email", customer.getEmail());
5    put("createdAt", Timestamp.valueOf(customer.getCreatedAt()));
6}};