code: public com.google.protobuf.ByteString
        getPostalCodeBytes() {
      java.lang.Object ref = postalCode_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        postalCode_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
docs: <pre>
  Optional. Postal code of the address. Not all countries use or require
  postal codes to be present, but where they are used, they may trigger
  additional validation with other parts of the address (e.g. state/zip
  validation in the U.S.A.).
  </pre>
  
  <code>string postal_code = 4;</code>