首先，你应该把你的代码放在类方法中，而不是类体中。其次，-ChangeStreamIterable<Document>迭代器元素是ChangeStreamDocument<Document>而不是Document。
总结一下：

public class MongoDBChangeStream {

    public void someMethod() {

        // connect to the local database server
        MongoClient mongoClient = MongoClients.create("db uri goes here");

        // Select the MongoDB database
        MongoDatabase database = mongoClient.getDatabase("MyDatabase");

        // Select the collection to query
        MongoCollection<Document> collection = database.getCollection("teams");

        // Create pipeline for operationType filter
        List<Bson> pipeline = Arrays.asList(
                Aggregates.match(
                        Filters.in(
                                "operationType",
                                Arrays.asList("insert", "update", "delete")
                        )));

        // Create the Change Stream
        ChangeStreamIterable<Document> changeStream = collection.watch(pipeline)
                .fullDocument(FullDocument.UPDATE_LOOKUP);

        // Iterate over the Change Stream
        for (ChangeStreamDocument<Document> changeEvent : changeStream) {
            // Process the change event here
        }
    }
}