code: public final void expurge() {
  		Reference<? extends E> obj;
  
  		final Iterator<R> iter = this.theSet.iterator();
  		R reference;
  		while (iter.hasNext()) {
  			reference = iter.next();
  			if (reference != null
  					&& ((reference.isEnqueued()) || (reference.get() == null))) {
  				reference.enqueue();
  				reference.clear();
  			}
  		}
  		while ((obj = this.queue.poll()) != null) {
  			obj.clear();
  			if (this.referenceType.isInstance(obj)) {
  				this.theSet.remove(this.referenceType.cast(obj));
  			}
  		}
  	}
docs: Clean the references that was released.