why flow.resource.name flow variable is showing as empty in trace of analytics data record

[Teja]

I need to log the conditional flow name of  transactions, found flow.resource.name flow variable in analytics data record of trace but this variable is showing as empty everytime even when im making call to a particular conditional flow.

Can someone tell me why is this var is showing with empty value?

I know to log the conditional flow name we can use current.flow.name var but to use this i need to create a var & assign with current.flow.name using assign msg policy and have to place that policy in each & every cond flows of all proxies. 

I dont want to implement in this way. I need a direct flow var for cond flow name and use that flow var in log policy of sharedflow so that i didn't require to update all the existing proxies