This repository works along with both the IBM Order Management On-Prem and IBM Order Management On-Cloud Developer courses. The code contained in this repository is for the entire courses. The courses expect that some code may not be available at certain points so it is better to download code as needed than everything at once. For example, the entity extensions will break your environment if you do not have the corresponding templates installed. And some java code expects the entities to be generated before they will work.
The On Prem course has a few workarounds required to make everything go smoothly. They are called out within the course material, but they are also located in the course folder here. You may not want to include that folder in your developer project.