code: public BsonDocument toBsonDocument() {
      final BsonDocument updateDescDoc = new BsonDocument();
      updateDescDoc.put(
          Fields.UPDATED_FIELDS_FIELD,
          this.getUpdatedFields());
  
      final BsonArray removedFields = new BsonArray();
      for (final String field : this.getRemovedFields()) {
        removedFields.add(new BsonString(field));
      }
      updateDescDoc.put(
          Fields.REMOVED_FIELDS_FIELD,
          removedFields);
  
      return updateDescDoc;
    }
docs: Converts this update description to its document representation as it would appear in a
  MongoDB Change Event.
  
  @return the update description document as it would appear in a change event