reactor-core/src/main/java/reactor/core/publisher/Flux.java
public final Flux<T> startWith(Publisher<? extends T> publisher) {
		if (this instanceof FluxConcatArray) {
			FluxConcatArray<T> fluxConcatArray = (FluxConcatArray<T>) this;
			return fluxConcatArray.concatAdditionalSourceFirst(publisher);
		}
		return concat(publisher, this);
	}
public final Flux<T> startWith(Publisher<? extends T> publisher) {
		if (this instanceof FluxConcatArray) {
			FluxConcatArray<T> fluxConcatArray = (FluxConcatArray<T>) this;
			return fluxConcatArray.concatAdditionalSourceFirst(publisher);
		}
		return concat(publisher, this);
	}
Prepend the given {@link Publisher} sequence to this {@link Flux} sequence.

<p>
<img class="marble" src="doc-files/marbles/startWithPublisher.svg" alt="">

@param publisher the Publisher whose values to prepend

@return a new {@link Flux} prefixed with the given {@link Publisher} sequence