public int getChunkSizeMB() {
        return chunkSizeMB;
    }
The split context used by {@link SplitStrategy} to split collection into a set of chunks for
MongoDB data source.
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/assigners/splitters/SplitContext.java