Prior to JDK 16, the `javac` compiler accepted annotations declared as local interfaces. Now the JLS 16 at section 14.3 forbids it. For example, the `javac` compiler had accepted code such as:

```
    class C {
        void m() {
            @interface A {}
        }
    }
```

This code is no longer acceptable according to Section [14.3] of the JLS 16:
"A local interface may be a normal interface (§9.1), but not an annotation interface (§9.6)."

To fix this issue, the `javac` compiler implementation has been synchronized with the JLS 16, so that annotation interfaces cannot be declared as local interfaces.