If there is ConnectionException happening while Collection.BulkWrite current version throw ConnectionException that makes no way to find what part of the BulkWrite was already processed by server. Driver should wrap the connection exception into BulkWriteException.
Upskip the following unified tests once the bug is fixed:
retriableWrites/bulkWrite.json:Second updateOne is never committed
retriableWrites/bulkWrite.json:Third updateOne is never committed