// when deep chains of futures exist resulting in a StackOverflowException. We could detect
    // arbitrary cycles using a thread local but this should be a good enough solution (it is also
    // what jdk collections do in these cases)
    try {
      if (o == this) {
        builder.append("this future");
      } else {
        builder.append(o);
      }

        state = other.state;

        notifyAndClearListeners();
        return;
      }

      /*
       * Almost everything in GWT is an AbstractFuture (which is as good as TrustedFuture under
       * GWT). But ImmediateFuture and UncheckedThrowingFuture aren't, so we still need this case.
       */
      try {
        forceSet(getDone(delegate));