public function setRequired( $state ) {
		$this->required = (bool)$state;
		if ( $this->required ) {
			$this->input->setAttributes( [ 'required' => 'required', 'aria-required' => 'true' ] );
			if ( $this->getIndicator() === null ) {
				$this->setIndicator( 'required' );
			}
		} else {
			$this->input->removeAttributes( [ 'required', 'aria-required' ] );
			if ( $this->getIndicator() === 'required' ) {
				$this->setIndicator( null );
			}
		}
		return $this;
	}