CDI: Investigate if interceptors should be enabled by default

Problem

• The engine-cdi module has two interceptors:
  • org.camunda.bpm.engine.cdi.impl.annotation.StartProcessInterceptor
  • org.camunda.bpm.engine.cdi.impl.annotation.CompleteTaskInterceptor
• In Weld-based CDI, interceptors can be enabled via the META-INF/beans.xml file.
  • By default, we enable our interceptors in this file.
• In Quarkus, the interceptors are automatically discovered and registered.

Solution Ideas

1. Interceptors are enabled by default; the user can exclude them via the property quarkus.arc.exclude-types in the application.properties file
   • Pros
     • engine-cdi behavior works out of the box
   • Cons
     • The annotation @Priority is not present on the interceptors, which is logged on the log level INFO => leads to confusion for the users.
       • We cannot directly add the @Priority annotation to the interceptors of the engine-cdi module since the annotation does not exist in CDI 1.0
         • We could extend the interceptors in the Quarkus extension and assign the @Priority annotation to get rid of the logs => this is not a very robust solution when we add more interceptors in the future
2. Interceptors are excluded by default; the user can enable them by extending and annotating the interceptors in the Quarkus application.
   • Pros

• • • Users have full control over exact annotations (e.g., priority, scope, etc.)
  • Cons
    • engine-cdi behavior does not work out of the box
    • Not robust since new interceptors we add in the future must be manually excluded in Quarkus
    • Higher documentation effort

Decision

Choosing solution #1 since it is better to maintain and less documentation effort. We accept for now that users see a log that the @Priority annotation is missing. With CAM-13841 we should evaluate if we can move our camunda-engine-cdi module to a higher CDI version (at least 1.1) and add this annotation to the module to get rid of the warning.