IoTCoreCustomAuthorizerResponse create invalid payalod #1131

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1. jlizen commented on Mar 19, 2026

   

   jlizen

   on Mar 19, 2026

   Last edited by jlizen

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   A non-breaking fix would be to keep Vec<Option<IamPolicyDocument>> and add a custom serializer that filters out None elements before writing the array. Since skip_serializing_if operates at the field level (not per-element), this would need a small custom serialize function, e.g.:

   fn serialize_non_null<S, T: Serialize>(values: &[Option<T>], serializer: S) -> Result<S::Ok, S::Error>
   where
       S: Serializer,
   {
       values.iter().flatten().collect::<Vec<_>>().serialize(serializer)
   }

   This would live in lambda-events/src/custom_serde/mod.rs alongside the other custom serde helpers, and be applied as #[serde(serialize_with = "serialize_non_null")] on the policy_documents field. The field should also get a doc comment noting that None elements are dropped during serialization since the IoT broker rejects them.

   Ideally the type would be Vec<IamPolicyDocument> since the broker never accepts null elements, but that would be a breaking change. The custom serializer is a good workaround that can ship without a major version bump.

   Glad to review a PR on this :)