Optional attributes on the futures API

[Marinell0]

Hello. Is there a reason why there are some critical attributes on Futures API that are optional?

Example: https://github.com/gateio/gateapi-nodejs/blob/master/model/futuresOrderBookItem.ts

In the FuturesOrderBookItem, p for price and s for size are both optional, even tho they are both always present.

Another example is the FuturesOrderBook itself: https://github.com/gateio/gateapi-nodejs/blob/master/model/futuresOrderBook.ts

current and update - as I can see from the documentation - are always present.

Thanks in advance =)