如何使用graphql-go获取嵌套对象的p.Args？

I'm trying to create mutation with graphql-go. I need to get object's nested element's args, but it's empty. How to fix it?

var mutationKittensType = graphql.NewObject(
    graphql.ObjectConfig{
        Name: "kittens",
        Fields: graphql.Fields{
            "littleName": &graphql.Field{
                Type: graphql.String,
            },
            "age": &graphql.Field{
                Type: graphql.Float,
            },
        },
    },
)

var mutationPropertiesType = graphql.NewObject(
    graphql.ObjectConfig{
        Name: "properties",
        Fields: graphql.Fields{
            "name": &graphql.Field{
                Type: graphql.String,
            },
            "kittens": &graphql.Field{
                Type: mutationKittensType,
            },
        },
    },
)

var mutationType = graphql.NewObject(
    graphql.ObjectConfig{
        Name: "create_cat",
        Fields: graphql.Fields{

            "type": &graphql.Field{
                Type: graphql.String,
            },
            "properties": &graphql.Field{
                Type: mutationPropertiesType,                  
            },

                Resolve: func(params graphql.ResolveParams) (interface{}, error) {


                    log.Println("params.Args ", params.Args)

My curl is:

      curl -XPOST http://localhost/graphql -H 'Content-Type: application/graphql' -d'mutation{create_cat(type:"persian", properties:{name: "alice", kittens:{littleName: "little alice", age: 1}}){type, properties{name, kittens:{littleName, age}}}}'

Terminal gives me this: params.Args map[ ]

Why is my params.Args empty and how to fix it?