match_nbt Loot Table Condition

Would like to see a condition for loot tables where loot can be conditional on matching nbt data from the item. 

Currently it's possible to create loot table entries for an item that can have nbt set individually using the   set_nbt function.  With a proposed match_nbt condition, one could first check if the item has identifying nbt details and conditionally provide loot.

A good example would be to conditionally match_nbt for an id that is in the SpawnData in the BlockEntityTag  of a minecraft:spawner item.

With this condition, it would then be possible to create a loot table for spawners that when a player breaks the spawner, and the conditions are such that they are using a tool with silk, that the looting table would drop a spawner, conditionally, from the list of entries, based on this match_nbt condition configured in each entry. 

Thus each entry is configured to match a specific entity id with the match_nbt condition, and drop a spawner set with custom nbt using the set_nbt function.