code: public Response post(String path, Object payload, Map<String, String> headers) throws IOException, RESTException {
          return postInternal(payload, new HttpPost(baseUrl + path), headers);
      }
docs: Performs POST request.
  
  @param path    Request path.
  @param payload Entity, which will be used as request payload.
  @param headers Map of HTTP request headers.
  @throws IOException   If error during HTTP connection or entity parsing occurs.
  @throws RESTException If HTTP response code is non OK.