docs: static ConfigException.NotResolved improveNotResolved(Path what,
              ConfigException.NotResolved original) {
          String newMessage = what.render()
                  + " has not been resolved, you need to call Config#resolve(),"
                  + " see API docs for Config#resolve()";
          if (newMessage.equals(original.getMessage()))
              return original;
          else
              return new ConfigException.NotResolved(newMessage, original);
      }