docs: private void cleanTable() {
          lock.lock();
          try {
              Reference<? extends TransactionConfidence> ref;
              while ((ref = referenceQueue.poll()) != null) {
                  // Find which transaction got deleted by the GC.
                  WeakConfidenceReference txRef = (WeakConfidenceReference) ref;
                  // And remove the associated map entry so the other bits of memory can also be reclaimed.
                  table.remove(txRef.hash);
              }
          } finally {
              lock.unlock();
          }
      }