code: static void initChains() {
  		if (config != null && config.getChains() != null) {
  			// add the chains to the handler list by id list.
  			for (String chainName : config.getChains().keySet()) {
  				List<String> chain = config.getChains().get(chainName);
  				List<HttpHandler> handlerChain = new ArrayList<>();
  				for (String chainItemName : chain) {
  					HttpHandler chainItem = handlers.get(chainItemName);
  					if (chainItem == null)
  						throw new RuntimeException("Chain " + chainName + " uses Unknown handler: " + chainItemName);
  					handlerChain.add(chainItem);
  				}
  				handlerListById.put(chainName, handlerChain);
  			}
  		}
  	}
docs: Construct chains of handlers, if any are configured NOTE: It is recommended
  to define reusable chains of handlers