Non-nullable property 'Greeting' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Converting null literal or possible null value to non-nullable type.

Possible null reference argument for parameter 'cnn' in 'Task<int> SqlMapper.ExecuteAsync(IDbConnection cnn, string sql, object? param = null, IDbTransaction? transaction = null, int? commandTimeout = null, CommandType? commandType = null)'.

Nullability of reference types in type of parameter 'value' of 'void AddGreetingMessageMapper.Context.set' doesn't match implicitly implemented member 'void IAmAMessageMapper<AddGreetingCommand>.Context.set' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'value' of 'void GreetingEventMessageMapper.Context.set' doesn't match implicitly implemented member 'void IAmAMessageMapper<GreetingEvent>.Context.set' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'value' of 'void GreetingEventAsyncMessageMapper.Context.set' doesn't match implicitly implemented member 'void IAmAMessageMapper<GreetingAsyncEvent>.Context.set' (possibly because of nullability attributes).

Non-nullable field '_transaction' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Possible null reference argument for parameter 'topic' in 'MessageHeader.MessageHeader(string messageId, RoutingKey topic, MessageType messageType, Uri? source = null, string? type = null, DateTimeOffset? timeStamp = null, string? correlationId = null, RoutingKey? replyTo = null, string contentType = "text/plain", string partitionKey = "", Uri? dataSchema = null, string? subject = null, int handledCount = 0, TimeSpan? delayed = null)'.

Possible null reference return.