How to list the files in all the subfolders of a SystemRepository

How to list the files in all the subfolders of a SystemRepository in a given directory.

Example path:

DCS001/R1/Device/Pressure/Pressure1.txt, Pressure2.txt, Pressure3.txt DCS001/R1/Device/Temperature/Temperature1.txt, Temperature2.txt, Temperature3.txt

We need a RestAPI/extension should have the following parameters:

Input file name: /SystemRepository/DCS001

Output: Pressure1.txt, Pressure2.txt, Pressure3.txt,Temperature1.txt, Temperature2.txt, Temperature3.txt

Kindly let us know the solution to achieve this usecase!