[handler-broker] Introduce JSONRecipient interface
[handler-broker] Introduce JSONRecipient interface

TheThingsNetwork/ttn,mgranberry/ttn,mgranberry/ttn,mgranberry/ttn,TheThingsNetwork/ttn,jvanmalder/ttn,jvanmalder/ttn,TheThingsNetwork/ttn,LoRaWanSoFa/ttn,LoRaWanSoFa/ttn,jvanmalder/ttn