A Study to Find Out How Nintedanib is Taken up in the Body and How Well it is Tolerated in Children and Adolescents With Interstitial Lung Disease (ILD)

A Double Blind, Randomised, Placebo-controlled Trial to Evaluate the Dose-exposure and Safety of Nintedanib Per os on Top of Standard of Care for 24 Weeks, Followed by Open Label Treatment With Nintedanib of Variable Duration, in Children and Adolescents (6 to 17 Year-old) With Clinically Significant Fibrosing Interstitial Lung Disease