private void TestRoundTrip(string expected, GeoJsonLinkedCoordinateReferenceSystem crs)
        {
            var json = crs.ToJson();
            Assert.AreEqual(expected, json);

            var rehydrated = BsonSerializer.Deserialize<GeoJsonLinkedCoordinateReferenceSystem>(json);
            Assert.AreEqual(expected, rehydrated.ToJson());
        }
        public void TestExampleFromSpecWithoutHRefType()
        {
            var crs = new GeoJsonLinkedCoordinateReferenceSystem("http://example.com/crs/42");
            var expected = "{ 'type' : 'link', 'properties' : { 'href' : 'http://example.com/crs/42' } }".Replace("'", "\"");

            TestRoundTrip(expected, (GeoJsonCoordinateReferenceSystem)crs);
            TestRoundTrip(expected, (GeoJsonLinkedCoordinateReferenceSystem)crs);
        }