Merges a later snapshot of a span into an earlier one.
OpenTelemetry reports each span twice — at onStart (creation-time
attributes only) and at onEnd (the full set) — and the two snapshots can
carry complementary data. This unions their attributes and lets any
defined field on incoming update existing, so nothing recorded at start
is lost when the span ends, and end-only fields (status, timings, token
usage, …) are filled in.
Merges a later snapshot of a span into an earlier one.
OpenTelemetry reports each span twice — at
onStart(creation-time attributes only) and atonEnd(the full set) — and the two snapshots can carry complementary data. This unions theirattributesand lets any defined field onincomingupdateexisting, so nothing recorded at start is lost when the span ends, and end-only fields (status, timings, token usage, …) are filled in.