message: Send PUB instead of HPUB if headers are set but empty
diff: @@ -573,19 +573,18 @@ impl Client {
  // Check if the client is closed.
  self.check_shutdown()?;
  - let op = if let Some(headers) = headers {
  - ClientOp::Hpub {
  + let op = match headers {
  + Some(headers) if !headers.is_empty() => ClientOp::Hpub {
  subject,
  reply_to,
  payload: msg,
  headers,
  - }
  - } else {
  - ClientOp::Pub {
  + },
  + _ => ClientOp::Pub {
  subject,
  reply_to,
  payload: msg,
  - }
  + },
  };
  let mut write = self.state.write.lock();
  