Problem

Because the current implementation of KVStates is a dedicated VirtualMap, it is straightforward to implement Store.size() methods like this one as here:

    @Override
    public long sizeOfState() {
        return tokenState.size();
    }

As all state is consolidated into one VirtualMap (aka MegaMap), the effort of preserving the OnDiskKVState.size() method will no longer be a good cost/benefit ratio. This means Stores need a new implementation of their e.g. sizeOfState() methods.

Solution

• Add a new singleton ENTITY_COUNTS and add a post upgrade step to update this state #17427
• Replace all Store.sizeOfState()  #17435
• Decrement entity type counters when KVState.remove() is called #17466
• Switch StoreMetrics.updateCount() callbacks to be done by a StateChangeListener with stateTypes() == Set.of(SINGLETON) instead of in OnDiskWritableKVState.
• Consolidate to use only one EntityType in com.hedera.node.app.spi.validation. Change all uses of com.hedera.node.config.types.EntityType to use com.hedera.node.app.spi.validation.EntityType

Testing

• Unit tests
• Load a state and validate the counts are correctly updating in Entity_Counts map
• All existing tests should pass