code: @Override
      public boolean queue(int bytes) {
          m_pendingTxnBytes += bytes;
          checkAndLogInvariants();
  
          if (m_pendingTxnBytes > MAX_DESIRED_PENDING_BYTES) {
              if (!m_hadBackPressure) {
                  hostLog.debug("TXN back pressure began");
                  m_hadBackPressure = true;
                  for (ACGMember m : m_members) {
                      m.onBackpressure();
                  }
              }
          }
          else if ((m_pendingTxnBytes < LESS_THAN_MAX_DESIRED_PENDING_BYTES) &&
                  (m_pendingTxnCount < LESS_THAN_MAX_DESIRED_PENDING_TXNS)) {
              if (m_hadBackPressure) {
                  hostLog.debug("TXN backpressure ended");
                  m_hadBackPressure = false;
                  for (ACGMember m : m_members) {
                      m.offBackpressure();
                  }
              }
          }
  
          return false;
      }
docs: /*
  Invoked when queueing response bytes back to a connection. Can be invoked with positive/negative
  values to indicate whether data is being flushed or added. The same resource pool counter is used
  to track pending responses as is used to track outstanding requests although only the bytes are being
  counted.
  
  Can signal start/stop backpressure when appropriate. The return value is not used and will be removed
  in the future.