docs: public final void expurgeQueuedReferences() {
  		Reference<? extends V> reference;
  		while ((reference = this.queue.poll()) != null) {
  			if (reference instanceof ReferencableValue<?, ?>) {
  				this.map.remove(((ReferencableValue<?, ?>) reference).getKey());
  			}
  			reference.clear();
  		}
  	}