reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final Mono<T> or(Mono<? extends T> other) {
		if (this instanceof MonoFirst) {
			MonoFirst<T> a = (MonoFirst<T>) this;
			Mono<T> result =  a.orAdditionalSource(other);
			if (result != null) {
				return result;
			}
		}
		return first(this, other);
	}
public final Mono<T> or(Mono<? extends T> other) {
		if (this instanceof MonoFirst) {
			MonoFirst<T> a = (MonoFirst<T>) this;
			Mono<T> result =  a.orAdditionalSource(other);
			if (result != null) {
				return result;
			}
		}
		return first(this, other);
	}
Emit the first available result from this mono or the other mono.

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

@param other the racing other {@link Mono} to compete with for the result

@return a new {@link Mono}
@see #first