### Question:
UserTokenFlow { public UserTokenFlow scopes(@Nonnull String... scopes) { Assertions.assertNotNull(scopes, "Scopes must not be null!"); this.scopes = Arrays.asList(scopes); return this; } UserTokenFlow(OAuth2TokenService tokenService, OAuth2ServiceEndpointsProvider endpointsProvider,
			ClientCredentials clientCredentials); UserTokenFlow token(String token); UserTokenFlow attributes(Map<String, String> additionalAuthorizationAttributes); UserTokenFlow subdomain(String subdomain); UserTokenFlow scopes(@Nonnull String... scopes); UserTokenFlow disableCache(boolean disableCache); OAuth2TokenResponse execute();  }### Answer:
@Test public void execute_withScopesSetToNull_throwsException() { assertThatThrownBy(() -> cut.scopes(null)).isInstanceOf(IllegalArgumentException.class); }