import java.math.BigInteger;
import java.util.concurrent.ExecutionException;
-import javax.annotation.Nullable;
+import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.genius.infra.Datastore.Configuration;
import org.opendaylight.genius.infra.TypedReadWriteTransaction;
import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.natservice.rev160111.ext.routers.Routers;