public void testDeleteGroupWithNonExistentGroupThrows() throws Exception {
        final DefaultGroupProvider provider = new DefaultGroupProvider();
        provider.createGroup("Test Group A");
        provider.createGroup("Test Group B");

        assertThrows(GroupNotFoundException.class,() -> provider.deleteGroup("Test Group C"));
    }
Verifies that {@link DefaultGroupProvider#deleteGroup(String)} throws a {@link GroupNotFoundException} when
attempting to delete a group by a name that does not exist
xmppserver/src/test/java/org/jivesoftware/openfire/group/DefaultGroupProviderTest.java