import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.verify;
-import com.google.common.base.Optional;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
+import java.util.Optional;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;