Ignore unrecognized value names in the response

The response might contain unknown fields.
We have to ignore these values instead of throwing exception.

```
The client MUST ignore unrecognized value names in the response.
https://tools.ietf.org/html/rfc6749#section-5.1
```

checkAllowedProperty throws exception if name is not in allowedProperties.
So, we need to use isAllowedProperty in order to ignore unknown fields.