[Authoring] AdaptiveCard XmlAttributes are wrong on new 1.4 card elements (DotNet)

Target Application

DotNet

Problem Description

XmlAttributes are missing or wrong

Card.Refresh.UserIds shouldn't be serialized if null

Action.Execute Data serializes as JSON instead of XML.

<?xml version="1.0" encoding="utf-8"?>
<Card xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version Major="1" Minor="4" />
  <TextBlock Size="ExtraLarge" Weight="Bolder" HorizontalAlignment="Center" Wrap="true">Super Deluxe Dice Roller</TextBlock>
  <Image Size="Large" Url="https://dice-card.azurewebsites.net/images/dice${DiceValue}.png" HorizontalAlignment="Center" />
  <ActionSet>
    <Action.Execute Title="Roll" Verb="roll">{
  "type": "adaptiveCard/action",
  "id": "${documentId}",
  "verb": "roll"
}</Action.Execute>
  </ActionSet>
  <Refresh UserIds="">
    <Action Title="Refresh" Verb="refresh">{
  "type": "adaptiveCard/action",
  "id": "${documentId}",
  "verb": "refresh"
}</Action>
  </Refresh>
</Card>

Expected Outcome

<?xml version="1.0" encoding="utf-8"?>
<Card xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version Major="1" Minor="4" />
  <TextBlock Size="ExtraLarge" Weight="Bolder" HorizontalAlignment="Center" Wrap="true">Super Deluxe Dice Roller</TextBlock>
  <Image Size="Large" Url="https://dice-card.azurewebsites.net/images/dice${DiceValue}.png" HorizontalAlignment="Center" />
  <ActionSet>
    <Action.Execute Title="Roll" Verb="roll">
       <Data id="${documentId}" verb="roll" />
  </Action.Execute>
  </ActionSet>
  <Refresh>
    <Action Title="Refresh" Verb="refresh">
        <Data id="${documentId}" verb="roll" />
    </Action>
  </Refresh>
</Card> 

Actual Outcome

Please describe what was the actual outcome

Repro Steps

Please enter the steps to reproduce the issue

Schema Version

What JSON Schema Version are you targeting?

Start by locating the .NET authoring XML serialization for Card.Refresh and Action.Execute, since no source files or tests are named. Compare the current output with the expected XML: null Refresh.UserIds should be omitted, and action data should be emitted as a Data element rather than JSON text. Done means the stated 1.4 elements serialize to the expected structure.