How to upgrade hibernate-jpamodelgen from 5 to 6?

Question

I have a working project with this maven section:

<plugin>
<groupId>org.bsc.maven</groupId>
<artifactId>maven-processor-plugin</artifactId>
<version>4.5</version>
<executions>
    <execution>
        <goals>
            <goal>process</goal>
        </goals>
        <phase>generate-sources</phase>
        <configuration>
            <processors>
                <processor>org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor</processor>
            </processors>
            <outputDirectory>${project.build.directory}/generated-sources/jpametamodel</outputDirectory>
            <overwrite>true</overwrite>
        </configuration>
    </execution>
</executions>
<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-jpamodelgen</artifactId>
        <version>${hibernate-jpamodelgen.version}</version>
    </dependency>
</dependencies>
</plugin>

When hibernate-jpamodelgen.version=5.6.14.Final, it works.

When I try to upgrade to 6.1.6.Final, the classes are not generated, hence I get compilation errors.