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 enable assertions (-source 1.4) and also want the compiled classes to be compatible with JVM 1.4 (-target 1.4), you can then put:
<project> [...] <build> [...] <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2.1</version> <configuration> <source>1.4</source> <target>1.4</target> </configuration> </plugin> </plugins> [...] </build> [...] </project>