class definitions could start with keyword enum

[ezksd]

Enum is a special type in java, which doesn't like enum in other programming languages. It's not a primitive type, enum has the same construct of class. We also consider it a syntax sugar to define a special class. And enum definition located at subchapter of classes in java language specification too.

enum Coin {
    PENNY(1), NICKEL(5), DIME(10), QUARTER(25);
    Coin(int value) { this.value = value; }

    private final int value;
    public int value() { return value; }
}

[joshgoebel]

Looks good. Please also update CHANGES.md