public function setIndicator( $indicator = null ) {
		if ( $this->indicatorName !== null ) {
			$this->indicator->removeClasses( [ 'oo-ui-indicator-' . $this->indicatorName ] );
		}
		if ( $indicator !== null ) {
			$this->indicator->addClasses( [ 'oo-ui-indicator-' . $indicator ] );
		}

		$this->indicatorName = $indicator;
		$this->toggleClasses( [ 'oo-ui-indicatorElement' ], (bool)$this->indicatorName );
		$this->indicator->toggleClasses( [ 'oo-ui-indicatorElement-noIndicator' ],
			!$this->indicatorName );

		return $this;
	}