timestampEpochNanos

Epoch-nanosecond timestamp at which the event occurred, from the producer's local clock — OTLP's timeUnixNano. null if the event time is unknown.

Distinct from observedEpochNanos, and the field to sort or print a timeline by: it is stamped where the line was logged, so it survives however long the record then waits to be written. The difference between the two is capture latency.