Given below type:

import (
    "database/sql"
    "encoding/json"
)

type MyNullString struct {
    sql.NullString
    json.Marshaler
    json.Unmarshaler
}

How to initialize below struct A?

type A struct{
     B MyNullString
}

Trying below syntax:

a := A{
  B: MyNullString{String: "aaa", Valid: true}
}

gives error: unknown field String in struct literal of type MyNullString

How to initialize member B of struct A?

Tried this answer