package org.opendaylight.mdsal.dom.store.inmemory;
-import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.CheckedFuture;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map.Entry;
+import java.util.Optional;
import java.util.concurrent.atomic.AtomicLong;
import org.opendaylight.mdsal.common.api.ReadFailedException;
import org.opendaylight.mdsal.dom.api.DOMDataTreeIdentifier;