@SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  private void addPendingString(StringBuilder builder) {
    // Capture current builder length so it can be truncated if this future ends up completing while
    // the toString is being calculated
    int truncateLength = builder.length();

    builder.append("PENDING");

    Object localValue = value;
    if (localValue instanceof SetFuture) {