Android Developer for Payments / Cashless ATM

Seeking Android Developer with experience in Payments, specifically Cashless ATM payments used by legal cannabis dispensaries in the US. We need someone to review existing source code for errors and add features (multiple processors, sub TIDs, etc). We will also have future work on integration to POS ( Flowhub, Leaf logix and others). We utilize Nexgo N5 terminals and Hyosung ATM machines. User interface, UI Flow and Admin all completed.