I am trying to write jUnit test cases for custom teaser component which extends the core Teaser component using the Delegation Pattern for Sling Models using "@Self @Via(type=ResourceSuperType.class)" as specified here: https://github.com/adobe/aem-core-wcm-components/wiki/Delegation-Pattern-for-Sling-Models
When I try to set the context (io.wcm.testing.mock.aem.junit5.AemContext) and adapt the context's request (I've tried resource as well) to the model I have created (like the "PageHeadline" from the example), I am getting a NullPointerException.

I am using AEM 6.5.2.0 and trying to run test cases in JUnit 5