Function encode_traces_v1 

pub fn encode_traces_v1<T: TraceData>(
    payload: &TracerPayload<T>,
    out: &mut impl Write,
    max_line_size: usize,
) -> Result<EncodeStats>

Encodes a v1 TracerPayload into newline-delimited JSON “log exporter” lines, writing them to out. Same framing, packing, and oversized-span dropping behavior as encode_traces — see its docs — but takes v1 TracerPayload/crate::span::v1::Span input and downgrades each span’s unified attribute model back to the meta/metrics-shaped wire span via [span_v1::LogSpanV1], since the JSON log wire contract (consumed by the Datadog Forwarder Lambda) is unchanged by the v1 migration. Payload-level env/app_version/ attributes are propagated into every span (lowest precedence, below chunk and span level) — same convention as the msgpack v0.4 downgrade encoder’s encode_payload_from_v1.

Errors

Returns any std::io::Error produced while writing to out.