DiskSpaceMonitorDescriptor currently contains the check
However, a return of 0 from File.getUsableSpace space is ambiguous. From the javadoc: "The number of available bytes on the partition or 0L if the abstract pathname does not name a partition. "
So a zero could mean "there is no partition" or that there are zero bytes left. In the /computer UI this shows up as "N/A" Free Disk Space.
Sample test program:
On a totally full partition
The test program will output:
I think this points to a solution: DiskSpaceMonitorDescriptor can also call getTotalSpace to determine what a zero from getUsableSpace really means.