});
EHCachingExchangeSource source = new EHCachingExchangeSource(underlying, _cacheManager);
assertEquals(0, getCount.get());
ExternalScheme scheme = ExternalScheme.of("Scheme");
ExternalId id = ExternalId.of(scheme, "Value");
Exchange get1 = source.getSingle(id);
assertEquals(1, getCount.get());
assertEquals(1, get1.getExternalIdBundle().size());
assertEquals(id, get1.getExternalIdBundle().getExternalId(scheme));
Exchange get2 = source.get(UniqueId.of("Test", "Foo", "0"));
assertEquals(1, getCount.get());
assertTrue(get1 == get2);
}