This commit adds a sameness-group config entry to the API and structs packages. It includes some validation logic and a new memdb index that tracks the default sameness-group for each partition. Sameness groups will simplify the effort of managing failovers / intentions / exports for peers and partitions.
Note that this change purely to introduce the configuration entry and does not include the full functionality of sameness-groups.
We have many indexer functions in Consul which take interface{} and type assert before building the index. We can use generics to get rid of the initial plumbing and pass around functions with better defined signatures. This has two benefits: 1) Less verbosity; 2) Developers can parse the argument types to memdb schemas without having to introspect the function for the type assertion.
Derek Menteer