### Question:
OAuth2ServiceConfigurationBuilder { public static OAuth2ServiceConfigurationBuilder forService(@Nonnull Service service) { Assertions.assertNotNull(service, "Service must not be null!"); OAuth2ServiceConfigurationBuilder instance = new OAuth2ServiceConfigurationBuilder(); instance.service = service; return instance; } private  OAuth2ServiceConfigurationBuilder(); static OAuth2ServiceConfigurationBuilder forService(@Nonnull Service service); static OAuth2ServiceConfigurationBuilder fromConfiguration(OAuth2ServiceConfiguration baseConfiguration); OAuth2ServiceConfigurationBuilder withClientId(String clientId); OAuth2ServiceConfigurationBuilder withClientSecret(String clientSecret); OAuth2ServiceConfigurationBuilder withUrl(String url); OAuth2ServiceConfigurationBuilder withProperty(String propertyName, String propertyValue); OAuth2ServiceConfigurationBuilder withProperties(Map<String, String> properties); OAuth2ServiceConfigurationBuilder runInLegacyMode(boolean isLegacyMode); OAuth2ServiceConfiguration build();  }### Answer:
@Test public void forService() { OAuth2ServiceConfiguration configuration = cut.build(); assertThat(configuration.getService()).isEqualTo(Service.XSUAA); }
@Test public void forService_serviceNull_throwsException() { assertThatThrownBy(() -> OAuth2ServiceConfigurationBuilder.forService(null)) .isInstanceOf(IllegalArgumentException.class) .hasMessageContaining("must not be null"); }