code: private void forceDecreaseKeyToMinimum(Node<K, V> n) {
          // if not root
          Node<K, V> y = n.parent;
          if (y != null) {
              cut(n, y);
              cascadingCut(y);
          }
          minRoot = n;
      }
docs: /*
  Decrease the key of a node to the minimum. Helper function for performing
  a delete operation. Does not change the node's actual key, but behaves as
  the key is the minimum key in the heap.