Empty query tree when using __Schema query

[kallyshall]

Hi, I was trying out his library (and am new to graphql).

so the query I used was
query { __schema { queryType { fields { name } } } }

and did something like result := fields.BuildTree(query, nil)

for result I was expecting something like {"__schema":"queryType", "__schema.queryType":"fields" ... } initially
but instead I got an empty map as result. is this working as expect?

Would be really appreciate if some lights can be shared on this, thanks!