Commenting post-close just to add ... uhm ... comments.
Managing java.io.tmpdir is almost a required aspect of handling concurrency issues when working on a
shared work environment such as a build server or a unix platform.
a) You have multiple users on the same machine.
b) Most of them are developers.
c) The developers are all working with a bea-maven-plugin (or something similar) that performs some
kind of task that uses the java.io.tmpdir to manage temporary files. However the implementation does
not create a uniq and/or random file or directory.
d) Developer 1 starts a long build using bea-maven-plugin
e) Developer 2 starts another build also using bea-maven-plugin, however his run now starts to pick up on the temporary files
that developer 1's instance of bea-maven-plugin is using.
In our work to make a build farm and or concurrent builds on a single server, I think it would be wise to keep
managing this variable, even on a per-project basis.