code: public Object[] toArray() {
          final ReentrantLock lock = this.lock;
          lock.lock();
          try {
              return Arrays.copyOf(queue, size);
          } finally {
              lock.unlock();
          }
      }
docs: Returns an array containing all of the elements in this queue.
  The returned array elements are in no particular order.
  
  <p>The returned array will be "safe" in that no references to it are
  maintained by this queue.  (In other words, this method must allocate
  a new array).  The caller is thus free to modify the returned array.
  
  <p>This method acts as bridge between array-based and collection-based
  APIs.
  
  @return an array containing all of the elements in this queue