How to restrict that subclass cannot be generic?

Compile time error: The generic class may not subclass java.lang.Throwable

public class TestGenericClass<E> extends Exception {

/*Above line will give compile error, the generic class TestGenericClass<E> may 
  not subclass java.lang.Throwable*/

    public TestGenericClass(String msg) {
        super(msg);
    }
}

Above compile time error is for the reason given in § jls-8.1.2 as below, and explained in this question:

It is a compile-time error if a generic class is a direct or indirect subclass of Throwable(§11.1.1).

This restriction is needed since the catch mechanism of the Java Virtual Machine works only with non-generic classes.

Question:

• How it is restricted that subclass of java.lang.Throwable will not be generic class?

• Or more generic question will be, how to restrict that subclasses of any class cannot be generic?

How it is restricted that subclass of java.lang.Throwable will not be generic class?

Here's how OpenJDK compiler performs the check:

import com.sun.tools.javac.code.Symbol.*;   

private void attribClassBody(Env<AttrContext> env, ClassSymbol c) {
    ....

    // Check that a generic class doesn't extend Throwable
    if (!c.type.allparams().isEmpty() && types.isSubtype(c.type, syms.throwableType))
        log.error(tree.extending.pos(), "generic.throwable");

As you can see forbidden type is kind of harcoded, so you can't use the same technique for your custom class without compiler code customization.

Full source code