Buildpack is not referring to the old one

[keraghu]

We are in a process of moving 100+ java apps from one foundation to another.
Initially we tried to use cf-copy-plugin (https://github.com/mevansam/cf-copy-plugin) to do this.
However, we realized that, cf-copy is not referring the online java-buildpack (https://github.com/cloudfoundry/java-buildpack#v4.6) and the reference in app manager shows N/A.
The cf app APP_NAME command shows something like this:
buildpack: java-buildpack=v3.8-offline-https://github.com/cloudfoundry/java-buildpack.git#29c79f2 , which does not show the buildpack we are referring in our code (manifest)
Can you suggest on this, or is it a known issue