The provided code sample makes use of features that are valid in Java interfaces as of Java 8. These features include default methods and static methods. The 'tare()', 'net()', and 'gross()' methods are properly defined with the 'default' keyword, allowing them to have implementations within the interface. The 'toUnit()' method is declared as 'private static', which is also a valid declaration within an interface to hide the implementation details from the implementing classes. 'public static final' variables are also allowed in interfaces. Thus, the code compiles without errors.