All cluster server parameters will be persisted to disk in the config.settings collection in every replica set in a cluster. These documents will all contain _id and generation fields, while the rest of the fields will be specific to the parameter. The ClusterServerParameter class will serve as a base class to enforce that all documents parsed from disk correctly have the _id and generation fields. All other parameter document classes will extend it via inline struct chaining. In order to validate this approach, the AuditConfigDocument for RAC will also be updated to extend this class when being read/written from disk.

1. Define ClusterServerParameter class in IDL
2. Refactor AuditConfigDocument such that it extends ClusterServerParameter via inline chained structs