Github user pnowojski commented on the issue: https://github.com/apache/flink/pull/6231 True, `checkNotNull(nestedSerializers);` is useless. Allowing nulls without enabled compile errors on violated `@Nullable` checks (this we can not enable in Flink) always leads to some null pointer exceptions and makes developing code unnecessary complicated - you need to manually walk through whole call stack up and down to confirm if null can/should be handled/supported/provided. This is annoying especially that in 99.9% cases completely avoidable - in this case, just call different constructor. I was looking for a way to call this other constructor in Scala and I couldn't (Scala seems to be annoying), however I found this workaround: https://github.com/apache/flink/pull/6392
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