See 15.9.5.1 for why it is explicitly allowed in the context of this test

/*
 * @test @(#)SuperNew3.java 1.2 02/08/26
 * @bug 4432312 4721003
 * @summary compiler crash with assertion failure (inner classes)
 * @author gafter
 *
 * @compile SuperNew3.java
 */

public class SuperNew3 {
    SuperNew3() {}
    SuperNew3(Object o) {}
    void foo() {
        class One extends SuperNew3 {}
        class Two extends SuperNew3 {
            Two() {
                super(new One() {
                        { new One(); }
                    });
            }
        }
    }
}