docs: public ActivityImpl getInnerActivity(PvmActivity miBodyActivity) {
      for (PvmActivity activity : miBodyActivity.getActivities()) {
        ActivityImpl innerActivity = (ActivityImpl) activity;
        // note that miBody can contains also a compensation handler
        if (!innerActivity.isCompensationHandler()) {
          return innerActivity;
        }
      }
      throw new ProcessEngineException("inner activity of multi instance body activity '" + miBodyActivity.getId() + "' not found");
    }