Hello, I have found this behaviour in the Java Client while switching from 2.7 to 2.8.
Short version of the story: - on 2.7.2 a null key is received as an empty key - on 2.8.0 a null key is received as a null key The behaviour of 2.8 is better, because it is what you expect. But if you migrate an application from 2.7.2 to 2.8 you can start to see Nulls instead of empty strings and this will lead to unpredictable behaviour and possibly NullPointerExceptions. We can accept the new behaviour but I would like to check if the community is aware of this and this is acceptable. This is the issue, with a reproducer https://github.com/apache/pulsar/issues/10625 Enrico
