-import com.google.common.base.Preconditions;
-import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
+import static java.util.Objects.requireNonNull;
+
+import java.util.Optional;
+import java.util.SortedSet;
+import org.eclipse.jdt.annotation.Nullable;
+import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
+import org.opendaylight.controller.cluster.datastore.DataStoreVersions;
+import org.opendaylight.yangtools.yang.data.tree.api.DataTreeModification;