code: public static Response delete(URI uri, Credentials credentials)
          throws URISyntaxException, HttpException {
          return send(new HttpDelete(uri), credentials, null);
      }
docs: Performs an HTTP DELETE on the given URI.
  Basic auth is used if both username and pw are not null.
  
  @param uri         The URI to connect to.
  @param credentials Instance implementing {@link Credentials} interface holding a set of credentials
  @return The HTTP response as Response object.
  @throws URISyntaxException
  @throws HttpException