CorreoAsync.java

List<CompletableFuture<Void>> futureList = getAllFuture();

CompletableFuture<Void> allFutureTogether = CompletableFuture.allOf(futureList.toArray());

allFutureTogether.whenComplete( (voidObject, error) -> {
        if ( error == null ){
          // all future ended successfully
          List<Correo> copyOfCorreos = new ArrayList<>(procesar);
          Correo lastCorreo = getLastSentCorreo(copyOfCorreos);
          configuracionCorreoService.save(lastCorreo);
        } else {
          // some thread has ended with error.... should I send an email with the error?
          log.error("OOPPS", error);
        }
});