code: public static Class<? extends ArgumentExtractor> getArgumentExtractor(Parameter parameter) {
          for (Annotation annotation : parameter.getAnnotations()) {
              if (annotation.annotationType().isAnnotationPresent(ExtractWith.class)) {
                  ExtractWith with = annotation.annotationType().getAnnotation(ExtractWith.class);
                  Class<? extends ArgumentExtractor> extractorClass = with.value();
                  return extractorClass;
              }
          }
          // if unspecified we use the ParamExtractor
          return ParamExtractor.class;
      }
docs: Returns the appropriate ArgumentExtractor to use for the controller method parameter.
  
  @param parameter
  @return an argument extractor