public static MongoClient clientFor(MongoDBSourceConfig sourceConfig) {
        return MongoClientPool.getInstance().getOrCreateMongoClient(sourceConfig);
    }
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