public void Dictionary_Add_NullValue()
        {
            IDictionary <string, object> attributes = new CloudEventAttributes(CloudEventsSpecVersion.Default, emptyExtensions);
            string attributeName = CloudEventAttributes.TypeAttributeName();

            Assert.Throws <ArgumentNullException>(() => attributes.Add(attributeName, null));
        }
        public void Collection_Add_NullValue()
        {
            ICollection <KeyValuePair <string, object> > attributes = new CloudEventAttributes(CloudEventsSpecVersion.Default, emptyExtensions);
            string attributeName = CloudEventAttributes.TypeAttributeName();
            var    pair          = KeyValuePair.Create(attributeName, default(object));

            Assert.Throws <InvalidOperationException>(() => attributes.Add(pair));
        }