What is ClassLoader?
Implement the getAllAnimals method. The method's pathToAnimals parameter is the absolute path to the directory where the compiled classes are saved. The path doesn't necessarily have a "/" at the end. Not all classes inherit the Animal interface.
extends vs super
All of the methods add the source to the destination. Add ?, extends, and super where needed: 1) methodOne must work with the same type; 2) methodTwo must add any descendants of T to a list that can only store T objects.
Wildcards for collections
The Solution class has 4 methods for working with lists: sum - Sums up all numeric elements of the list, multiply - Multiplies all numeric elements of the list, concat - Concatenates all elements of the list into a single String.