Method fromFuture

src/main/java/io/reactivex/rxjava3/core/Flowable.java:2300–2307

Converts a Future into a Publisher. The operator calls Future#get(), which is a blocking method, on the subscription thread. It is recommend

(@NonNull Future<? extends T> future)

     * @see #fromCompletionStage(CompletionStage)
     */
    @CheckReturnValue
    @NonNull
    @BackpressureSupport(BackpressureKind.FULL)
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <@NonNull T> Flowable<T> fromFuture(@NonNull Future<? extends T> future) {
        Objects.requireNonNull(future, "future is null");
        return RxJavaPlugins.onAssembly(new FlowableFromFuture<>(future, 0L, null));
    }

    /**
     * Converts a {@link Future} into a {@link Publisher}, with a timeout on the {@code Future}.