Create a collection and put a Int number into the collection val list = listOf<Int>(1) and figure out which library function of which class is implicitly called before this happens. The answer should be in the form <class name>.<method name>.
Use Force Step Into to quickly find a method.
Tip: Create some collection of Int. Put a breakpoint on this line. To get the answer, you need to press Force Step Into in the Debug tool window.