JSON RPC on Google Ad Manager internal endpoint

I'm trying to create custom Pricing Rules on Google Ad Manager programatically, but the GAM API doesn't have CRUD Pricing Rules endpoints implemented yet, so i'm looking another ways to do.

I tried to Inspect Element on GAM webapp (admanager.google.com) and on Network tab i seen when i save a Pricing Rule the browser makes a call to this endpoint:

https://admanager.google.com/dfp/v2/exchange/rpc/PricingRuleService?methodName=createPricingRule

So, i believe that i can use this endpoint to create custom Pricing Rules, the problem is on the request body, the webapp places this JSON:

{
    "method": "createPricingRule",
    "params": {
        "2": {
            "1119": "29015379732033875438"
        },
        "1532": {
            "1025": 1925346054,
            "2103": {
                "163": {},
                "881": {
                    "2253": {
                        "660": 2531
                    }
                },
                "1085": {
                    "3075": [
                        {
                            "259": "2032"
                        }
                    ]
                },
                "2395": {},
                "2527": {},
                "2921": {
                    "1104": false
                },
                "3417": {
                    "1225": {
                        "3786": false
                    },
                    "1543": {
                        "290": false
                    },
                    "2381": {},
                    "3125": {}
                },
                "3792": true
            },
            "2377": false,
            "3171": [
                {
                    "903": 66989036,
                    "1021": {
                        "385": "USD",
                        "2182": "200000"
                    },
                    "3684": {
                        "403": {},
                        "1337": {},
                        "2077": {},
                        "2929": {},
                        "3785": {
                            "1033": true
                        }
                    }
                }
            ],
            "3844": "TestReport.Country.AdUnitName.3"
        }
    }
}

I don't understand the keys of this JSON, there no properties, only strings with numbers and values.

Any idea or help?

Thanks! Regards