import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;
-import com.google.common.base.Optional;
import com.google.common.collect.ImmutableMap;
import com.google.common.io.ByteStreams;
import com.google.common.util.concurrent.Futures;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.Map;
+import java.util.Optional;
import org.opendaylight.netconf.sal.connect.netconf.schema.NetconfRemoteSchemaYangSourceProvider.NetconfYangTextSchemaSource;
import org.opendaylight.netconf.sal.connect.util.RemoteDeviceId;
import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceException;