docs: public static CompletionStage<Void> allOf(CompletionStage<?>... stages) {
        AggregateCompletionStage<Void> aggregateCompletionStage = null;
        for (CompletionStage<?> stage : stages) {
           if (!isCompletedSuccessfully(stage)) {
              if (aggregateCompletionStage == null) {
                 aggregateCompletionStage = CompletionStages.aggregateCompletionStage();
              }
              aggregateCompletionStage.dependsOn(stage);
           }
        }
  
        return aggregateCompletionStage != null ? aggregateCompletionStage.freeze() : CompletableFutures.completedNull();
     }