Add build-time weaving to your pom.xml

<plugin>
    <groupId>com.ethlo.persistence.tools</groupId>
    <artifactId>eclipselink-maven-plugin</artifactId>
    <version>2.7.1.1</version>
    <dependencies> 
        <dependency>
            <groupId>javax.annotation</groupId>
            <artifactId>javax.annotation-api</artifactId>
            <version>1.3.1</version>
        </dependency>
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.0</version>
        </dependency>
    </dependencies>
    <executions>
        <execution>
            <id>weave</id>
            <phase>process-classes</phase>
            <goals>
                <goal>weave</goal> 
            </goals>
        </execution>
        <execution>
            <id>modelgen</id>
            <phase>generate-sources</phase>
            <goals>
                <goal>modelgen</goal> 
            </goals>
        </execution>
    </executions>
</plugin>