Maven BuildNumber plugin problem

[FrancescoMez79]

Dear Support, we have a Jhipster application that use this application version in pom.xml:

0.0.2-SNAPSHOT

We want to add the buildnumber to our application version. We have found the plugin Build-number: https://www.mojohaus.org/buildnumber-maven-plugin/usage.html

We have added in pom.xml under pluginManagement section the plugin "buildnumber-maven-plugin" ..

org.codehaus.mojo buildnumber-maven-plugin 3.0.0 validate create true true .. and added the field "finalName" with -${buildNumber}: ..

    <finalName>${project.artifactId}-${project.version}-${buildNumber}</finalName>
</build>..

After run the build command : ./mvnw clean install

in target we see that the buildnumber is setted to null: myapp-0.0.2-SNAPSHOT-null.jar

Can you please help me to understand the problem?

Thanks, Francesco