The following line is probably intended to track whether all requests are retryable:

https://github.com/mongodb/mongo-java-driver/blob/master/driver-core/src/main/com/mongodb/operation/BulkWriteBatch.java#L104

and should probably be:

writeRequestsAreRetryable = writeRequestsAreRetryable && isRetryable(writeRequest);

As currently written it is only tracking whether the last request is retryable.