Ticket: Get Comments

I created this query and imported to Java from Compas;

How do I convert it to BSON?

Arrays.asList(new Document("lookup", new Document("from", "comments") .append("let", new Document("movieIdFromMovie", "_id"))
.append(“pipeline”, Arrays.asList(new Document("$match",
new Document("$expr",
new Document("$eq", Arrays.asList("$movie_id", “$$movieIdFromMovie”))))))
.append(“as”, “movie_comments”)))