Publisher Bid Modifier Object

{
   // other Campaign fields...
   "publisher_bid_modifier": {
      "values": []
   }
}

{
   // other Campaign fields...
   "publisher_bid_modifier": {
      "values": [
         {
            "target": "demo-site-1",
            "cpc_modification": 1.5
         },
         {
            "target": "demo-site-2",
            "cpc_modification": 0.9
         }
      ]
   }
}