Jira customization sometimes requires to modify Jira property files, like we can see at http://confluence.atlassian.com/display/JIRA/Translating+JIRA or like this is the case when installing some specific plugIns.

However, when upgrading the Jira product, such customizations are overwritten, and must be carefully applied again, one by one, which unfortunately increases the cost of a product upgrade.

Here is a very simple idea that would allow Jira administrators to customize product properties with flawless upgrade:

. under WEB-INF folder, add a new folder dedicated for resources customization. Let's call it 'config'. The structure of that folder will have to follow the package arborescence implemented in Jira.

. when we want to customize a property of a property file, then we place a properties file with the same name and arborescence of the original one, but containing only the customized property, not the unchanged ones

When the JIra engine is loading properties/resources, it proceeds as usual, and, finally, loads the ones from that 'config' folder, then overriding the system properties.

The benefits are:
. Customization are localized in the 'config' folder, not mixed with default settings
. When upgrading, this folder is not overwritten, and we can easily use it on other installations.

That technic could also be used for templates, where only the complete file would be overriden.