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

        assertThrows(GroupAlreadyExistsException.class, () -> provider.setName("Test Group A", "Test Group B"));
    }
Verifies that {@link DefaultGroupProvider#setName(String, String)} throws a {@link GroupAlreadyExistsException}
when attempting to rename a group to name of another existing group
xmppserver/src/test/java/org/jivesoftware/openfire/group/DefaultGroupProviderTest.java