code: @Reference(cardinality = ReferenceCardinality.MULTIPLE, policy = ReferencePolicy.DYNAMIC)
      protected void setJobExecutionEndCallbackService(IJobExecutionEndCallbackService reference) {
          jobExecutionEndCallbacks.add(reference);
      }
docs: Note the list is not going to have a well-defined order, so it is of limited use.
  We probably want to revisit this with some kind of priority/order based on ranking to make
  it more useful.
  
  @param reference