Serializing F# objects with interfaces ignores interface members

[kellerd]

Test Script

#I "../packages/Newtonsoft.Json/lib/net45"
#r "Newtonsoft.Json.dll"
open Newtonsoft.Json
type IFoo = abstract FooMember: int

type IBar =
inherit IFoo
abstract BarMember: int

// Approach 1: Implement IFoo "explicitly".
// In the object browser, you will see both IFoo and IBar as parents of FooBar.
type FooBar =
{Name:string}
interface IFoo with member this.FooMember = 0
interface IBar with member this.BarMember = 0

// Approach 2: Implement IFoo "implicitly" (as part of IBar).
// In the object browser, you will only see IBar as parent of FooBar.
type FooBar2(name : string) =
member x.Name2 = name
interface IBar with
member this.FooMember = 0
member this.BarMember = 0

let one = JsonConvert.SerializeObject({Name="One"})
let two = JsonConvert.SerializeObject(FooBar2("Two"))

Output

val one : string = "{"Name":"One"}"
val two : string = "{"Name2":"Two"}"

Expected output

val one : string = "{"Name":"One", "FooMember":0, "BarMember":0}"
val two : string = "{"Name2":"Two", "FooMember":0, "BarMember":0}"