private UsernamePassword(String username, String password) {
        this.username = username;
        this.password = password;
    }
@Test
    public void testUsernamePassword() {
        UsernamePassword usernamePassword = UsernamePassword.usernamePassword(username, password);

        assertNotNull("The usernamePassword should not be null.", usernamePassword);
        assertEquals("The username should match the expected value.", username, usernamePassword.username());
        assertEquals("The password should match the expected value.", password, usernamePassword.password());
    }