java - Apache commons configuration regex expression interpretation -

on current project, use apache commons configuration read configuration files our applications , tests.

i've noticed peculiar behaviour regular expressions in configuration files.

we have property regex can find correct files in input folders, example:

file_pattern = (xpto(\d{3})).input 

this find files name starts xpto followed 3 digits, example xpto001.input.

the problem in systems expression works, while in others same libs requires \d escaped, works like:

file_pattern = (xpto(\\d{3})).input 

i've read documentation of apache commons configuration , java properties , failed find configuration/setting change this.

can me identify affects behaviour?

thank you.