code: public CombinableConfig combine(Config... fallbackConfigs) {
          CombinableConfig newConfig = this;
          for (Config fallback : fallbackConfigs) {
              newConfig = new ConfigWithFallback(newConfig, fallback);
          }
          return newConfig;
      }
docs: combines this configuration with given ones. Given configuration doesn't override existing one.
  
  @param fallbackConfigs the configurations to combine
  @return this instance for chaining