the field name is excluded from the result because start with a lower case .

type ColorGroup struct {
		ID     int
		name   string
		Colors []string
	}

Does this issue reproduce with the latest release?

yes

What did you do?

a example , 99% inspired by the example from your documentation

https://go.dev/play/p/ZaxfyRsRg_g

What did you expect to see?

{"ID":1,"name":"Reds","Colors":["Crimson","Red","Ruby","Maroon"]}

What did you see instead?

json result has only 2 fields

{"ID":1,"Colors":["Crimson","Red","Ruby","Maroon"]}

this issue is so obvious , that i think i miss a word in this documentation https://pkg.go.dev/encoding/json#Marshal
but i read twice , and i did not anything