Rewards Destination

[0x19dG87]

@davekaj

As fat new function has been added to the protocol recently, I would like to view this information on the subgraph.

rewardsDestination property for the GraphAccount entity.
sentRewards property for the Indexer entity.

Let me know if it is possible and if I need to create a pull request.

[juanmardefago]

Would be a good addition, and easy to add. Adding to the backlog