code: public HttpClient setRequestMethod(final String rMethod) throws HibiscusException {
  
          if (null == rMethod || false == validHttpRequestMethods.contains(rMethod)) {
              throw new HibiscusException(rMethod + " is not a valid HTTP Request Method");
          }
  
          requestMethod = rMethod;
          return this;
      }
docs: Must be One of HEAD, GET, POST, PUT or DELETE
  
  @param rMethod
  @throws HibiscusException If the request method is not allowed or valid