VB -> C#: named optional parameter that's a C# keyword isn't always escaped

[TymurGubayev]

VB.Net input code

    Sub S1(Optional a As Object = Nothing, Optional [default] As String = "")
    End Sub

    Sub S()
        S1(, "a")
    End Sub

Erroneous output

        public void S1(object a = null, string @default = "")
        {
        }

        public void S()
        {
            this.S1(default: "a");
        }

Expected output

        public void S1(object a = null, string @default = "")
        {
        }

        public void S()
        {
            this.S1(@default: "a");
        }

Details

• Product in use: VS extension
• Version in use: 5143c08297ae65cb7490ae768645f61131bf96be
• Did you see it working in a previous version, which? no
• Any other relevant information to the issue, or your interest in contributing a fix.