fix for Missing or empty metadata values are not allowed with POST /v2/op/update
fix for Missing or empty metadata values are not allowed with POST /v2/op/update

Fiware/data.Orion,telefonicaid/fiware-orion,telefonicaid/fiware-orion,telefonicaid/fiware-orion,Fiware/data.Orion,telefonicaid/fiware-orion,Fiware/data.Orion,Fiware/data.Orion,Fiware/data.Orion,telefonicaid/fiware-orion,telefonicaid/fiware-orion,Fiware/data.Orion