The following run-time exception is raised

    > Exception in thread "main" java.lang.IllegalAccessError:
    > failed to access class pkg.Exceptions$EBase from class ExceptionsTest
    > (pkg.Exceptions$EBase and ExceptionsTest are in unnamed module of loader 'app')
    >     at ExceptionsTest.main(ExceptionsTest.java:8)

when running "java ExceptionsTest" program with

    > package pkg;
    > public class Exceptions {
    >     private static class EBase extends Exception {
    >         public void m() {}
    >     }
    >     public static class E1 extends EBase {}
    >     public static class E2 extends EBase {}
    > }

and

    > import pkg.Exceptions;
    > public class ExceptionsTest {
    >     public static void main(String[] args) {
    >         try {
    >             m1();
    >         } catch (Exceptions.E1 | Exceptions.E2 e) {
    >             e.m();
    >         }
    >     }
    >     private static void m1() throws Exceptions.E1, Exceptions.E2 {
    >         throw new Exceptions.E1();
    >     }
    > }

Source(s):
- https://gist.github.com/DasBrain/61d2859a66183d29cb2eb9bf4cc1c81b
- https://twitter.com/lukaseder/status/1544713480024068098