MongoDB Java driver has been impacted by two server bugs, SERVER-113344 and SERVER-113026, and failed to parse the unexpected bulkWrite responses produced by these bugs.

This ticket is to investigate whether the C driver is affected by the same server behavior when using client bulkWrite and mitigate the issue.

On a sharded collection where the operation goes through the "without shard key" path (the filter does not contain the shard key):

• SERVER-113344: For client bulkWrite with errorsOnly: true, the server still returns a successful per-operation result in the cursor instead of returning only errors.
  • In the Java driver, we now ignore such unexpected successful results in the cursor (we do not return them to the application).

• SERVER-113026: For client bulkWrite with errorsOnly: false, nModified is not included by the server in the individual operation result (in the cursor).
  • In the Java driver, we now treat a missing nModified in this case as 0 when decoding.

The Java driver previously hit parsing/decoding errors when it encountered these unexpected reply shapes. Reproduction steps are described in this document (they apply to both server issues): Link.