Message Key Lost in Retry and DLQ

[xwwwx]

I noticed that after using ReconsumeLaterAsync, the messages that originally had a value for the key have an empty key when consumed again.

I found that the issue is mainly in the function getOptionalKey in the file src\Pulsar.Client\Internal\DeadLetters.fs. This function only sets the PartitionKey when message.Key is empty.

    let getOptionalKey (message: Message<'T>) =
            if String.IsNullOrEmpty(%message.Key) then
                Some { PartitionKey = message.Key; IsBase64Encoded =  message.HasBase64EncodedKey  }
            else
                None

[Lanayx]

Thanks for noticing! I've made a fix in 3.5.2, please verify