Make AbstractMongoSessionConverter injectable

While it defaults to the coverter based on whether or not Jackson is on the classpath, this attribute must be overridable based on whatever is in the application context.

src/main/java/org/springframework/session/data/mongo/ReactiveMongoOperationsSessionRepository.java

@@ -19,6 +19,7 @@ import static org.springframework.session.data.mongo.MongoSessionUtils.*;
 
 import org.bson.Document;
 import reactor.core.publisher.Mono;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.mongodb.core.ReactiveMongoOperations;
 import org.springframework.session.ReactorSessionRepository;
 
@@ -119,6 +120,7 @@ public class ReactiveMongoOperationsSessionRepository implements ReactorSessionR
 		return this.mongoOperations.findById(id, Document.class, this.collectionName);
 	}
 
+	@Autowired(required = false)
 	public void setMongoSessionConverter(AbstractMongoSessionConverter mongoSessionConverter) {
 		this.mongoSessionConverter = mongoSessionConverter;
 	}