Define the Java version in Maven

Directly in the pom.xml (resource definition is also included):

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
...
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
            <includes>
                <include>**/*</include>
            </includes>
            <excludes>
                <exclude>profiles/**</exclude>
            </excludes>
            </resource>
            <resource>
                <directory>src/main/resources/profiles/${profile.name}</directory>
                <includes>
                    <include>*.properties</include>
                    <include>*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>