Set the size of the built file system

[maximebochon]

I didn't find how to set the memory space size of the built file system.

I looked at the MemoryFileSystemBuilder JavaDoc and at the README, but this feature seems to be missing.

My use case is to test a "no space left on device" situation by setting a low size on the test file system.

[marschall]

There isn’t currently a way to do this. MemoryFileStore doesn't currently track the whole used space so there is currently not a way to check if we exceed this.