code: protected void resize(int newCapacity) {
          parent = Arrays.copyOf(parent, newCapacity);
          left = Arrays.copyOf(left, newCapacity);
          right = Arrays.copyOf(right, newCapacity);
          depth = Arrays.copyOf(depth, newCapacity);
      }
docs: Resize internal storage in order to be able to store data for nodes up to
  <code>newCapacity</code> (excluded).