pom.xml

<dependencies>
    <dependency>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.4.0</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <artifactId>exec-maven-plugin</artifactId>
            <groupId>org.codehaus.mojo</groupId>
            <executions>
                <execution>
                    <id>grunt-default</id>
                    <phase>generate-resources</phase>
                    <configuration>
                        <workingDirectory>WebContent</workingDirectory>
                        <executable>grunt</executable>
                        <arguments>
                            <argument>build</argument>
                        </arguments>
                    </configuration>
                    <goals>
                        <goal>exec</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>