-import com.google.common.base.Preconditions;
-import com.google.common.collect.Sets;
-import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import static java.util.Objects.requireNonNull;
+
+import java.util.Collections;
+import org.eclipse.jdt.annotation.NonNull;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;