public static String commandErrorMessage(BsonDocument commandResult) {
        return Optional.ofNullable(commandResult)
                .map(doc -> doc.getString("errmsg"))
                .map(BsonString::getValue)
                .orElse(null);
    }
Utilities of MongoDB operations.
Copy from com.ververica:flink-connector-mongodb-cdc:2.3.0.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/mongodb-cdc/src/main/java/org/apache/inlong/sort/cdc/mongodb/source/utils/MongoUtils.java