Renamed ApplePickingStrategy to be Predicate.
Made interface Predicate generic.
Wrote intent code to pass a method as a parameter in test the_green_apple_picker_should_pick_green_apples_only().
Fixed compiler error: Created and implemented method Apple.filterApples().
Fixed compiler error: Created method Apple.isGreenApple().
Wrote intent code to pass a method as a parameter in test the_heavy_apple_picker_should_pick_heavy_apples_only().
Fixed compiler error and made all tests to pass: Created method Apple.isHeavyApple().