Resharding (and other PrimaryOnlyServices) maintain a list of non-fatal error codes here. However, there have been cases where we needed to add new error codes to this list, but were reluctant to add them to this main list in the interest of minimizing changes to unrelated code. This has led to two more variants, kRetryabilityPredicateIncludeWriteConcernTimeout and kRetryabilityPredicateIncludeLockTimeoutAndWriteConcern. We should try to collapse all of these definitions into a single notion of retryable error codes for PrimaryOnlyServices.