How can the Android OS identify AndroidX fragments if they are obfuscated?

Question

I am doing a reverse-engineering work related to Android fragments. I found out in many apks (decompiled with apktool, dexToJar, ...), the androidx.fragment.app.Fragment class is obfuscated. In most of the cases the class members are obfuscated, while in some minor cases, the class name is even obfuscated. I am wondering in these cases, how can the Android OS identify AndroidX fragments in an app at runtime?