Docker Image buld from Scratch using the brand new Ubuntu 20.04 LTE + IBM J9 + OpenLiberty 19 All Dockerfile has coments indicating the origin of each part.
Docker file avaiable at:
https://github.com/gknepper/Ubuntu20.04OpenLiberty19Scratch
Image avaiable at:
https://hub.docker.com/r/gabrielkm/ubuntu2004openliberty19scratch