Subscriptions to low level configurations take preference over high level configurations,
and subscriptions to same configuration level are additive. For example, if you add two
subscriptions to "root" with condition set to "build successful" and "build failed"
respectively, and if you've checked "descendents" option, you will get notifications
for all builds of "root/project1". However, if you add an additional subscription to
"root/project1" with condition set to "build is broken", you will only receive
notifications from this configuration when its builds are broken.