nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of java.util.ArrayList (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value (‘[https://c-ssl.duitang.com/uploads/blog/202108/04/20210804120908_96d67.jpg]’)
这个错误实际上是由于controller层加了@Validated校验，传入files参数格式不对引起
