fn unrecognised_keys(
pairs: &[(Value, Value)],
peer: Option<&str>,
data: &EventData,
) -> Vec<(Value, Value)>Expand description
Every entry on pairs that the event decoded from it does not write back
out of a field of its own. See unrecognised, which the header uses for
the same reason.
One difference from the header’s use of it is worth naming, because it
decides which entry of a duplicate pair survives. A getter here searches
for the first entry it can use, where the header’s lookup returns the
first entry for a key whatever it holds. So on a file repeating a key with
two different types — "sid": "x" and then "sid": 9 — the field takes
the second and the walk drops the first. Both were lost before this walk
existed, and SPEC.md leaves readers free to disagree over which of a
duplicate pair wins, so nothing may depend on which one it is.