innerBoundaryIsParser(node, objectStack) {
    /** @type {Array<number>|undefined} */
    const flatLinearRing = pushParseAndPop(
      undefined,
      this.RING_PARSERS,
      node,
      objectStack,
      this,
    );
    if (flatLinearRing) {
      const flatLinearRings =
        /** @type {Array<Array<number>>} */
        (objectStack[objectStack.length - 1]);
      flatLinearRings.push(flatLinearRing);
    }
  }
@param {Element} node Node.
@param {Array<*>} objectStack Object stack.