在Windows环境下邮件服务能够正常使用，但是在Linux环境下，邮件服务报错，无法发送邮件。

在启动SpringBoot项目的时候，项目却报错误信息：

DefaultObjectWrapper.incompatibleImprovements was set to the object returned by Configuration.getVersion(). That defeats the purpose of incompatibleImprovements, and makes upgrading FreeMarker a potentially breaking change. Also, this probably won’t be allowed starting from 2.4.0. Instead, set incompatibleImprovements to the highest concrete version that’s known to be compatible with your application.
Configuration.incompatibleImprovements was set to the object returned by Configuration.getVersion(). That defeats the purpose of incompatibleImprovements, and makes upgrading FreeMarker a potentially breaking change. Also, this probably won’t be allowed starting from 2.4.0. Instead, set incompatibleImprovements to the highest concrete version that’s known to be compatible with your application.

在每一个学习Java的同学，都应该写过下面的这一段代码。

在项目中使用了Swagger作为项目接口API说明文档，但是在启动项目的时候，启动日志中报了一个警告信息，虽然最终并不影响项目功能的使用，但是却依旧让人看得不舒服。