pub fn Build() -> String
Build a W3C traceparent header value for an outgoing crossing. Same trace ID across the whole process; fresh span ID per call.
traceparent
Example: 00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01
00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01