message: opentelemetry: filter out invalid parent contexts
diff: @@ -90,6 +90,7 @@ pub(crate) fn build_span_context(
  let (trace_id, trace_flags) = builder
  .parent_context
  .as_ref()
  + .filter(|parent_context| parent_context.is_valid())
  .map(|parent_context| (parent_context.trace_id(), parent_context.trace_flags()))
  .unwrap_or_else(|| {
  let trace_id = builder.trace_id.expect("trace_id should exist");
  