Magento2: get custom customer attribute value

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer;
use Magento\Customer\Api\CustomerRepositoryInterface;

class EnablePaymentMethodByCustomerAttribute implements ObserverInterface
{
    /** @var CustomerRepositoryInterface */
    protected $_customerRepository;
    protected $_logger;

    /**
     * 
     * @param CustomerRepositoryInterface $customerRepository
     * @param \Psr\Log\LoggerInterface $logger
     */
    public function __construct(
        CustomerRepositoryInterface $customerRepository,
        \Psr\Log\LoggerInterface $logger
    )
    {
        $this->_customerRepository = $customerRepository;
        $this->_logger = $logger;
    }

    /**
     * 
     * @param Observer $observer
     */
    public function execute(Observer $observer)
    {
        $customer = $observer->getCustomer();
        $customer->getData('custom_attribute_name');
    }
}