docs: public Set<MigratingProcessElementInstance> getChildren() {
      Set<MigratingProcessElementInstance> childInstances = new HashSet<MigratingProcessElementInstance>();
      childInstances.addAll(childActivityInstances);
      childInstances.addAll(childTransitionInstances);
      childInstances.addAll(childCompensationInstances);
      childInstances.addAll(childCompensationSubscriptionInstances);
      return childInstances;
    }