String getUserName() {
    return configuration.get(USER_NAME_ATTRIBUTE).orElseThrow(() -> new IllegalArgumentException("User name attribute is missing"));
  }
@Test
  public void return_user_name_attribute() {
    settings.setProperty("sonar.auth.saml.user.name", "userName");

    assertThat(underTest.getUserName()).isEqualTo("userName");
  }