PortfoliosService portfoliosService = IntxServiceFactory.createPortfoliosService(client);
UpdatePortfolioRequest request = new UpdatePortfolioRequest.Builder()
    .portfolioId("portfolio_id")
    .name("new_portfolio_name")
    .build();
UpdatePortfolioResponse response = portfoliosService.updatePortfolio(request);

For more information, please visit the INTX Java SDK.