/*
               * requireNonNull is safe because we've initialized these if
               * !GENERATE_CANCELLATION_CAUSES.
               *
               * TODO(cpovirk): Maybe it would be cleaner to define a CancellationSupplier interface
               * with two implementations, one that contains causeless Cancellation instances and

   * @Nullable X>, then users might pass a TypeParameter<Y>, where Y is a subtype of X, while still
   * passing a TypeToken<X>. This would be invalid. Maybe we could accept a TypeParameter<@PolyNull
   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but

         *
         * OK, it's technically possible for this to fail in the presence of unsafe publishing, as
         * discussed in the comments in TimeoutFuture. TODO(cpovirk): Maybe check for null before
         * calling recordOutputCancellation?
         */
        requireNonNull(localState).recordOutputCancellation(interruptIfRunning);
        return true;
      }
      return false;