Usage of API documented as @since 1.6+ This inspection finds all usages of methods that have @since tag in their documentation. This may be useful when development is performed under newer SDK version as the target platform for production
File ->Project Structure->Project Settings -> Modules -> 你的Module名字 -> Sources -> Language Level->选个默认的就行。
intellij 出现“Usage of API documented as @since 1.8+”的解决办法
原文：https://www.cnblogs.com/zouzhe0/p/11445499.html