Parsing error for optional method in interface

[kupriyanenko]

example:

interface IRootContainerAPI {
  getElement?(): HTMLElement;
  attachToElement?(element: HTMLElement): void;
  setWidth?(width: number): void;
  getWidth?(): number;
  setHeight?(height: number): void;
  getHeight?(): number;
  setFillAllSpace?(flag: boolean): void;
  hide?(): void;
  show?(): void;
}

error:

An error occurred while building documentation. { SyntaxError: "Player public methods" documentation source (src/core/default-modules.ts) - Unexpected token, expected : (44:13)
  42 | /** */
  43 | interface IRootContainerAPI {
> 44 |   getElement?(): HTMLElement;