Method withPlaceholderTemplate

src/cdk/drag-drop/drag-ref.ts:485–488

* Registers the template that should be used for the drag placeholder. * @param template Template that from which to stamp out the placeholder.

(template: DragHelperTemplate | null)

   * @param template Template that from which to stamp out the placeholder.
   */
  withPlaceholderTemplate(template: DragHelperTemplate | null): this {
    this._placeholderTemplate = template;
    return this;
  }

  /**
   * Sets an alternate drag root element. The root element is the element that will be moved as