Some interface methods have a body. Such methods are called default
Although default methods are implemented, you cannot invoke them directly from
an interface. You still need to have an object of a class that implements the
interface.
If you want to customize a default method in a class, just override it like
a regular method.
Sometimes default methods are huge. To make it possible to decompose such methods,
Java allows declaring private methods inside an interface
That allows you to add new methods to the existing interface without changing all
classes that implement the interface