Release a new version of https://github.com/camunda/camunda-template-engines-jsr223 that uses Velocity 2.1. This should be a new major version of camunda-template-engines-jsr223, as velocity seems to have some breaking changes from version 1.7 to 2.1.

We should also update the Camunda BOM for 7.13 accordingly and inform our users via the migration guide.