Method concat

src/main/java/io/reactivex/rxjava3/core/Maybe.java:186–193

Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by an Iterable sequence as a Flowable sequence.

(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources)

     * @throws NullPointerException if {@code sources} is {@code null}
     */
    @BackpressureSupport(BackpressureKind.FULL)
    @CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <@NonNull T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
        Objects.requireNonNull(sources, "sources is null");
        return RxJavaPlugins.onAssembly(new MaybeConcatIterable<>(sources));
    }

    /**
     * Returns a {@link Flowable} that emits the items emitted by two {@link MaybeSource}s, one after the other.