code: public AssetHandler maxAge(final String maxAge) {
      Try.apply(() -> Long.parseLong(maxAge))
          .recover(x -> ConfigFactory.empty()
              .withValue("v", ConfigValueFactory.fromAnyRef(maxAge))
              .getDuration("v")
              .getSeconds())
          .onSuccess(this::maxAge);
      return this;
    }
docs: Parse value as {@link Duration}. If the value is already a number then it uses as seconds.
  Otherwise, it parse expressions like: 8m, 1h, 365d, etc...
  
  @param maxAge Set the cache header max-age value in seconds.
  @return This handler.