code: public Result proceed() throws Exception {
          if (iterator == null) {
              iterator = chain.listIterator();
          }
          if (!iterator.hasNext()) {
              throw new IllegalStateException("Reached the end of the chain without result.");
          }
          Filter filter = iterator.next();
          return filter.call(route, this);
      }
docs: Calls the next interceptors.
  
  @return the result from the next interceptor
  @throws java.lang.Exception if the invocation fails.