public Collection<String> getUsernames() {
        return provider.getUsernames();
    }
@Test
    public void getUserNamesWillGetAListOfUserNames()  throws Exception{
    	final Collection<String> result = userManager.getUsernames();
    	assertThat(result.contains(USER_ID), is(true));
        assertThat(result.contains(USER_ID_2), is(true));
        assertThat(result.contains("not exists name"), is(false));
    }