What's the role of the StateSender.sol contract?

StateSender contract is one of the genesis contracts which was deployed on the Ethereum network by the polygon team, this contract is responsible for keeping track of the mapping of registered root and child addresses. It has a method called stateSync() which is provoked internally every time we want to communicate between chains and it also emits an event called StateSynced which the Polygon validators on the Heimdal layer actively listen to and then pass it on to the Bor layer through an API call.