The following program:

import java.util.Arrays;

public class DuplicateFields {

    interface I {
        int X = 42;
    }

    interface J extends I {}

    static abstract class C implements I, J {}

    public static void main(String[] args) {
        J.class.getFields();
        System.out.println(Arrays.toString(C.class.getFields()));
    }
}


Prints:

[public static final int DuplicateFields$I.X, public static final int DuplicateFields$I.X]