Initialize a specific component of the cache identified by the key.
E.g. In Maxvars, a specific maxvar can be reinitiliazed from the database.
Don't call this method directly. Instead call
MXServer.reloadCache(String, String, boolean).
Return the maximo cache instance.
This method is called to obtain the cache object.
In multi-tenancy enviroment, if the cache is specific to the tenant, this method
should return the cache instance based on the tenant id of the context. In non-multi-tenant environment, or the cache
is not tenant specific, then it returns to the one cache object.