code: public void addVertxHolder(VertxHolder holder) {
  
      if (vertxPlatforms.containsValue(holder.getVertx())) {
        if (!this.vertxHolders.contains(holder)) {
          log.log(Level.INFO, "Adding Vertx Holder: " + holder);
          this.vertxHolders.add(holder);
        } else {
          log.log(Level.WARNING, "Vertx Holder: " + holder
              + " has been added already.");
        }
      } else {
        log.log(Level.SEVERE, "Vertx Holder: " + holder
            + " is out of management.");
      }
    }
docs: Adds VertxHolder to be recorded.
  
  @param holder
  the VertxHolder