getRedeliveryCount always return 0

Hello,

Is there a way to make `message.getRedeliveryCount()` return the number of time a message has been redelivered?
I hope it's not a problem between the chair and the keyboard, but in my case, the function always returns 0.

I tried to let the default parameters on `subscribe`, but it doesn't change anything.
There is no disconnection of the client between each redelivery.
The message is well nack each time.

i use `pulsar-client` v1.8 and `kezhenxu94/pulsar` pulsar container (pulsar 2.10.0).

Start with the message.getRedeliveryCount() and subscribe entry points, then reproduce the behavior using pulsar-client v1.8 against Pulsar 2.10.0 while acknowledging with nack and keeping the client connected. Done means the redelivery count reflects repeated deliveries, or the issue documents the supported behavior and cause of the constant zero.

索引モデルが issue の本文から書いたものです。