Use the com.mongodb.lang.NonNull annotation instead
package com.mongodb.reactivestreams.client.internal.gridfs;
+import com.mongodb.lang.NonNull;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.core.publisher.BaseSubscriber;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink;
-import reactor.util.annotation.NonNull;
import java.nio.Buffer;
import java.nio.ByteBuffer;
