private function addMissingRequirementMessage( Whip_Requirement $requirement ) {
		switch ( $requirement->component() ) {
			case 'php':
				$this->messageManager->addMessage( new Whip_UpgradePhpMessage( $this->textdomain ) );
				break;
			default:
				$this->messageManager->addMessage( new Whip_InvalidVersionRequirementMessage( $requirement, $this->configuration->configuredVersion( $requirement ) ) );
				break;
		}
	}