code: @SuppressWarnings("unchecked")
  	MonoDelayUntil<T> copyWithNewTriggerGenerator(boolean delayError,
  			Function<? super T, ? extends Publisher<?>> triggerGenerator) {
  		Objects.requireNonNull(triggerGenerator, "triggerGenerator");
  		Function<? super T, ? extends Publisher<?>>[] oldTriggers = this.otherGenerators;
  		Function<? super T, ? extends Publisher<?>>[] newTriggers = new Function[oldTriggers.length + 1];
  		System.arraycopy(oldTriggers, 0, newTriggers, 0, oldTriggers.length);
  		newTriggers[oldTriggers.length] = triggerGenerator;
  		return new MonoDelayUntil<>(this.source, newTriggers);
  	}
docs: Add a trigger generator to wait for.
  @param delayError the delayError parameter for the trigger being added, ignored if already true
  @param triggerGenerator the new trigger to add to the copy of the operator
  @return a new {@link MonoDelayUntil} instance with same source but additional trigger generator