Sometimes when you may need to compile a certain project to a different version than what you are currently using. The javac can accept such command using -source and -target. The Compiler Plugin can also be configured to provide these options during compilation.
For example, if you want to use the Java 8 language features (-source 1.8) and also want the compiled classes to be compatible with JVM 1.8 (-target 1.8), you can either add the two following properties, which are the default property names for the plugin parameters:
<project>
[...]
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
[...]
</project>
OR configure the plugin directly:
<project>
[...]
<build>
[...]
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
[...]
</build>
[...]
</project>