Why shouldn’t Java enum literals be able to have generic type parameters?

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This has been discussed as of JEP-301 Enhanced Enums, which was withdrawn, regrettably. The example given in the JEP is, which is precisely what I was looking for:

enum Argument<X> { // declares generic enum
   STRING<String>(String.class), 
   INTEGER<Integer>(Integer.class), ... ;

   Class<X> clazz;

   Argument(Class<X> clazz) { this.clazz = clazz; }

   Class<X> getClazz() { return clazz; }
}

Class<String> cs = Argument.STRING.getClazz(); //uses sharper typing of enum constant

Unfortunately, the JEP was struggling with significant issues, which couldn’t be resolved: http://mail.openjdk.java.net/pipermail/amber-spec-experts/2017-May/000041.html

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