packages/material-ui/src/Modal/ModalManager.ts/ModalManager/mount
class ModalManager:  mount(modal: Modal, props: ManagedModalProps): void {
    const containerIndex = findIndexOf(
      this.containers,
      (item) => item.modals.indexOf(modal) !== -1,
    );
    const containerInfo = this.containers[containerIndex];

    if (!containerInfo.restore) {
      containerInfo.restore = handleContainer(containerInfo, props);
    }
  }