I have the following java code that creates Bson filters (working as intended).

However when I try to add a projection to my filter I then get:

'unknown operator: $project' on server

What is the issue here within my code?

 private Bson createFilter(String name) {

        List<Bson> collectionFilters = new ArrayList<>();

        if (name != null) {
            filters.add(eq("person_name", name));
        }

        collectionFilters.add(projectCollectionFields());

        return and(collectionFilters);
    }

    private Bson projectCollectionFields() {
        return Aggregates.project(new Document()
                .append("_id", new Document("$cond", Arrays.asList(
                        new Document("$ne", Arrays.asList("$_id", null)),
                        "$_id",
                        "$$REMOVE"
                )))
                .append("name", new Document("$cond", Arrays.asList(
                        new Document("$ne", Arrays.asList("$person_name", null)),
                        "$person_name",
                        "$$REMOVE"
                )))
                .append("date", new Document("$cond", Arrays.asList(
                        new Document("$ne", Arrays.asList("$date_added", null)),
                        "$date_added",
                        "$$REMOVE"
                ))));
    }