This property is not honoured by NetBeans when it starts a Gradle daemon, so I end up with a Gradle daemon using the "default" amount of RAM, which on some machines is too little, and on some is too much (it's 25% of system RAM).
I'm guessing this is because it's loaded by the wrapper, not the daemon, because other properties like org.gradle.daemon.idletimeout=360000 are honoured by NB's gradle daemon.
The other effect of not loading that property is that I get multiple gradle dameons running, each consuming 16Gb of RAM, because they're "incompatible", so fixing this will save me about 16Gb of RAM per system.
I'm a bit shaky on this bug report, but ... I think this is what's going on.
(footnote: oh dear, Shevek broke something again, what on earth is that idiot doing with NetBeans and why can't Shevek just behave like a "normal" developer )