[BUG] Assumption that cache eviction does not happen

[snazy]

From #465: "The existing code assumes that all of the entities are in the cache once the Resolver runs. That process puts all of the entities and their grants into the cache so that by the time the Authorizer retrieves the grants, it fetches them from the cache."

It sounds like that the code really relies on the entities being available from the cache, which means that no eviction must happen. If eviction happens (which must be assumed to happen at any point in time to any cache entry) requests can fail at any time w/ misleading errors and/or wrong information.

[collado-mike]

At least in the linked PR, all cache lookups invoke entityCache.getOrLoadEntityById - this will validate that the cache entry is present and do the lookup if it is not. The "assumption" mentioned is on the performance characteristics, not the correctness of the code.