code: public com.google.protobuf.ByteString
        getCurrencyCodeBytes() {
      java.lang.Object ref = currencyCode_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        currencyCode_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
docs: <pre>
  The 3-letter currency code defined in ISO 4217.
  </pre>
  
  <code>string currency_code = 1;</code>