You set it in pom.xml so that idea will not adjust jdk to 1.5 when running. .

<properties>
   <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>          
   <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
   <java.version>1.8</java.version>
   <maven.compiler.source>1.8</maven.compiler.source>
   <maven.compiler.target>1.8</maven.compiler.target>
   <encoding>UTF-8</encoding>
</properties>

This shouldn’t be a big problem
The compilation environment should be in dependencies.
This language level seems to be the prompts and suggestions of the editor interface, which allows you to write code that is compatible with your features in 1.5. If you do not change the editor, you will get an error, but there will be no problem compiling with 1.7.