docs: @NotNull public static <T> Single<T> from(@NotNull final ApolloStoreOperation<T> operation) {
      checkNotNull(operation, "operation == null");
      return Single.create(new Single.OnSubscribe<T>() {
        @Override
        public void call(final SingleSubscriber<? super T> subscriber) {
          operation.enqueue(new ApolloStoreOperation.Callback<T>() {
            @Override public void onSuccess(T result) {
              subscriber.onSuccess(result);
            }
  
            @Override public void onFailure(Throwable t) {
              subscriber.onError(t);
            }
          });
        }
      });
    }