code: public Descriptor withPathParamSerializer(Type pathParamType, PathParamSerializer<?> pathParamSerializer) {
          return replaceAllPathParamSerializers(pathParamSerializers.plus(pathParamType, pathParamSerializer));
      }
docs: Provide a custom path param serializer for the given path param type.
  
  @param pathParamType The path param type.
  @param pathParamSerializer The path param serializer.
  @return A copy of this descriptor.