[Bug] Kyverno's sum function requires at least 1 element in the array

[AlessandroPomponio]

Page link

https://kyverno.io/docs/writing-policies/jmespath/#sum

Description

The page mentions that the sum function in Kyverno is a custom version that has been augmented compared to the baseline JMESPath specification.

The page, however, does not mention the caveat that the sum function in Kyverno requires at least 1 element in the array, while the JMESPath specification says that the result should be 0.

This can be checked with the following: echo '{"input":[]}' | kyverno jp query "sum(input)"
And seen in the source code: https://github.com/kyverno/kyverno/blob/f7a962fd11846ebebf85e33cfaf85dc92f6d117e/pkg/engine/jmespath/functions.go#L858

Expected behavior

I would expect to see a note about this behaviour, as it deviates from the JMESPath spec

Slack discussion

No response

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