Nullability of reference types in return type of 'ICollection<string>? SubscriptionCollection.Keys.get' doesn't match implicitly implemented member 'ICollection<string> IDictionary<string, Subscription>.Keys.get' (possibly because of nullability attributes).

Nullability of reference types in return type of 'ICollection<Subscription>? SubscriptionCollection.Values.get' doesn't match implicitly implemented member 'ICollection<Subscription> IDictionary<string, Subscription>.Values.get' (possibly because of nullability attributes).

Dereference of a possibly null reference.

Non-nullable property 'Endpoint' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'SupportVersions' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Possible null reference argument for parameter 'server' in '(string Host, int Port) Utils.GetHostAndPort(string server)'.

Dereference of a possibly null reference.

The field 'RecordAccumulator._flushesInProgress' is assigned but its value is never used

XML comment has a typeparam tag for 'TKey', but there is no type parameter by that name