code: @SuppressWarnings("unchecked")
      private void addToRootList(Node<K, V> n) {
          if (minRoot == null) {
              n.next = n;
              n.prev = n;
              minRoot = n;
              roots = 1;
          } else {
              n.next = minRoot.next;
              n.prev = minRoot;
              minRoot.next.prev = n;
              minRoot.next = n;
  
              int c;
              if (comparator == null) {
                  c = ((Comparable<? super K>) n.key).compareTo(minRoot.key);
              } else {
                  c = comparator.compare(n.key, minRoot.key);
              }
              if (c < 0) {
                  minRoot = n;
              }
              roots++;
          }
      }
docs: /*
  Add a node to the root list and update the minimum.