presto-mongodb/src/main/java/io/prestosql/plugin/mongodb/MongoSession.java/MongoSession/collectionExists
class MongoSession:    public boolean collectionExists(MongoDatabase db, String collectionName)
    {
        for (String name : db.listCollectionNames()) {
            if (name.equalsIgnoreCase(collectionName)) {
                return true;
            }
        }
        return false;
    }