Specify JDK Version in Maven

<properties>
 <jdk.version>1.6</jdk.version>
</properties>

<build>
 <plugins>
  <plugin>
   <groupId>org.apache.maven.plugins</groupId>
   <artifactId>maven-compiler-plugin</artifactId>
   <version>2.3.1</version>
   <configuration>
    <source>${jdk.version}</source>
    <target>${jdk.version}</target>
   </configuration>
  </plugin>
 </plugins>
</build>