@Test
public void testWithCredentials() {

  Credentials credentials = Mockito.mock(Credentials.class);
  HttpJsonCallContext emptyContext = HttpJsonCallContext.createDefault();
  Truth.assertThat(emptyContext.getCredentials()).isNull();
  HttpJsonCallContext context = emptyContext.withCredentials(credentials);
  Truth.assertThat(context.getCredentials()).isNotNull();
}