reactor-core/src/main/java/reactor/core/publisher/Flux.java
public final <E extends Throwable> Flux<T> onErrorResume(Class<E> type,
			Function<? super E, ? extends Publisher<? extends T>> fallback) {
		Objects.requireNonNull(type, "type");
		@SuppressWarnings("unchecked")
		Function<? super Throwable, Publisher<? extends T>> handler = (Function<?
				super Throwable, Publisher<? extends T>>)fallback;
		return onErrorResume(type::isInstance, handler);
	}
public final <E extends Throwable> Flux<T> onErrorResume(Class<E> type,
			Function<? super E, ? extends Publisher<? extends T>> fallback) {
		Objects.requireNonNull(type, "type");
		@SuppressWarnings("unchecked")
		Function<? super Throwable, Publisher<? extends T>> handler = (Function<?
				super Throwable, Publisher<? extends T>>)fallback;
		return onErrorResume(type::isInstance, handler);
	}
Subscribe to a fallback publisher when an error matching the given type
occurs, using a function to choose the fallback depending on the error.
<p>
<img class="marble" src="doc-files/marbles/onErrorResumeForFlux.svg" alt="">

@param type the error type to match
@param fallback the function to choose the fallback to an alternative {@link Publisher}
@param <E> the error type

@return a {@link Flux} falling back upon source onError