Control over the EntityId in Entity Stores

[gravelld]

I've been looking at optimising my use of Xodus and realised calls to getProperty() can be quite expensive.

In my case, I am indexing the properties of files. In this case, the file locations are static and could be used as identifiers.

For entities where we have some identifier which we can guarantee to be unique, would it be worth allowing the client to specify their own getLocalId()?

This way, it's one less getProperty() call...