public Collection<JID> getAdmins() {
        return administrators;
    }
@Test
    public void testReflectedInCacheGroupDeleted() throws Exception
    {
        // Setup test fixture.
        final String groupName = "unit-test-group-p";
        final Group group = groupManager.createGroup(groupName);
        final JID testUser = new JID("unit-test-user-p", "example.org", null);
        group.getAdmins().add(testUser);

        // Execute system under test.
        groupManager.deleteGroup(group);
        final CacheableOptional<Group> cachedGroup = groupCache.get(groupName);

        // Verify results.
        assertNull(cachedGroup.get());
    }