code: public CoinbaseSubscription getCoinbaseSubscription(String subscriptionId) throws IOException {
  
      final CoinbaseSubscription subscription =
          coinbase.getsSubscription(
              subscriptionId,
              exchange.getExchangeSpecification().getApiKey(),
              signatureCreator,
              exchange.getNonceFactory());
      return subscription;
    }
docs: Authenticated resource that lets you (as a merchant) show an individual subscription than a
  customer has created with you. This call returns a {@code CoinbaseSubscription} object where
  you are the merchant.
  
  @param subscriptionId
  @return
  @throws IOException
  @see <a
  href="https://coinbase.com/api/doc/1.0/subscribers/show.html">coinbase.com/api/doc/1.0/subscribers/show.html</a>