docs: public void setPendingContainer(AckingContainer container) {
          Preconditions.checkNotNull(m_pendingContainer.get() != null, "Pending container must be null.");
          if (m_closed) {
              // A very slow export decoder must have noticed the export processor shutting down
              exportLog.info("Discarding stale pending container");
              container.internalDiscard();
          } else {
              m_pendingContainer.set(container);
          }
      }