docs: public static void clear() {
          JobContext ctx = current_.get();
          if (null != ctx) {
              ctx.bag_.clear();
              JobContext parent = ctx.parent;
              if (null != parent) {
                  current_.set(parent);
                  ctx.parent = null;
              } else {
                  current_.remove();
                  Act.eventBus().trigger(new JobContextDestroyed(ctx));
              }
          }
      }