Have you tried placing that properties file in the WEB-INF/classes folder of the war or even at the root of a .jar in the WEB-INF/lib folder?
I tried all the option. Placing property file to WEB-INF/lib, /classes as well.
In my scenario, Documentum client apis looking for that property file to load.For making documentum related jar available to my app, i have already created module and put all the relevent jar in the module. One of that jar is dependent on this property file which it's not able to find.