If this is some external dependency which doesn't come out of the box in AEM and which you are trying to use in AEM, then you will have to embed that jar as well in your package. You can check this
https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/embedding-and-installing-e...
But essentially you can go to your all/pom.xml. Locate filevault-package-maven-plugin config section and add new embed entry for your jar and respective dependency as well. For E.g:
<embedded>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.resource.filter</artifactId>
<target>/apps/eon-de-relaunch-vendor-packages/application/install</target>
</embedded>
And the dependency
<!-- Sling Resource Filter -->
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.resource.filter</artifactId>
<version>1.0.0</version>
<scope>provided</scope>
</dependency>
This is just sample, you need to provide your own dependency details.
Hope this helps