DRIVERS-2619 : This includes a fix to the fle2v2-CreateCollection test assertions. Update the fle2v2-CreateCollection test to this commit: mongodb/specifications@e59a0ac . If the test previously passed, this may suggest a bug in the test runner of the Client Side Encryption legacy format. The matching behavior of `command_started_event` is expected to reject extra captured fields in the subdocuments of `command`. This suggests test runners are expected not to allow extra fields in subdocuments of the command. Test runners are not expected to handle null values specially for subdocuments of the command.