message: Avoid unnecessary copy due to folly::get_optional in processAckFrame
  Summary: As titled
diff: @@ -388,7 +388,7 @@ AckEvent processAckFrame(
  const bool retransmission = ([&outstandingPacket, &ackedFrame]() {
  // in some cases (some unit tests), stream details are not available
  // in these cases, we assume it is not a retransmission
  - if (const auto maybeStreamDetails = folly::get_optional(
  + if (const auto* maybeStreamDetails = folly::get_ptr(
  outstandingPacket.metadata.detailsPerStream,
  ackedFrame.streamId)) {
  const auto& maybeFirstNewStreamByteOffset =
  