China should fully expect the US and Australia to either bordering on intruding Indonesian airspace, or ouright disregard Indonesian airspace sovereignty, or both, in times of war with China.
To counter this, China should start working towards striking backdoor deals with Indonesia, which would allow Indonesia to play as a vital defensive barrier along China's southern frontier, while refrained from becoming an active participant of the war itself.
It would be better if the China-Indonesia agreements on neutrality were made more publicly
Too many Americans think Indonesia is going to roll over and agree to whatever the Americans want.
Indonesia as a neutral nation is perfectly fine from China's point of view.