Typically indexes on primaries are built via a user command. However there are a few instances where index builds can complete on a node that identifies as a primary, but managed by the IndexBuilder class. Specifically:

• Primary catchup
• Primary drain
• Started on a secondary, but complete after a step-up

Primaries (and other states) do not timestamp index completion. For primaries, it was expected that committing the index build writes an oplog entry, timestamping the transaction.

Instead, consider having callers of MultiIndexBlock manage timestamping the write.