Need detailed steps for "Designing the application logic for a Kogito service using DMN and BPMN"

In "Designing the application logic for a Kogito service using DMN and BPMN" section, copy&paste DMN/BPMN file contents works fine but if users follow manual steps to design DMN/BPMN, users would stumble sometimes (e.g. may fail with "java.lang.NullPointerException: Kie DMN API parameter 'model' cannot be null.").

Requires some more detailed steps.

https://docs.jboss.org/kogito/release/latest/html_single/#proc_kogito-designing-app