Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5735
@aljoscha Would be interested in your opinion here.
This is basically one of two ways to improve the handling of default values:
1. Add a default value supplier on the state descriptor (this approach).
Advantage is that you can use this to backwards compatibly handle the previous
cases of default values (including the starting value for folding state)
2. Add a `T getOrDefault(Supplier<T>)` method to `ValueState`. This might
me almost simpler to do even, and more flexible as it allows for different
default values in different contexts. This can get inefficient though when
users naively create an anonymous class for the supplier (probably not a big
deal any more since lambdas) and it breaks with the current approach, meaning
we two different ways for default values that need to work together, one of
which is deprecated, but still needs to be supported until Flink 2.0
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