@Override
	public Set<SystemScope> fromStrings(Set<String> scope) {
		if (scope == null) {
			return null;
		} else {
			return new LinkedHashSet<>(Collections2.filter(Collections2.transform(scope, stringToSystemScope), Predicates.notNull()));
		}
	}
@Test
	public void fromStrings() {

		// check null condition
		assertThat(service.fromStrings(null), is(nullValue()));

		assertThat(service.fromStrings(allScopeStrings), equalTo(allScopes));

		assertThat(service.fromStrings(allScopeStringsWithValue), equalTo(allScopesWithValue));
	}