The REST server currently handles 0 values for timeToLiveSeconds and maxIdleTimeSeconds like this:
|timeToLiveSeconds||maxIdleTimeSeconds||used lifespan||used maxIdle|
|0||0||default from config||default from config|
|nothing or >0||0||whatever came or -1||default from config|
|0||nothing or >0||literally 0(entry expires immediately)||whatever came or -1|
After discussion with Galder, the last line doesn't really make sense, and the better way would be to use default for timeToLive as well.