Choice.Value can't be nulll

Describe the bug

There is no clear division of responsibility between the two Value fields:

• If you only set the ActionCard.Value, you will receive a runtime error: Object reference not set to an instance of an object.
• If you set only the Choice.Value, an ActionCard will be displayed but it will not perform a post.
• If you set the both fields, you will not know which ones you will receive in the post.

To Reproduce

Use Choice as follow:

new Choice()
{
    Action = new CardAction(
        type:ActionTypes.PostBack, 
        title:"Select this item",
        value:1)
}

Expected behavior

Use the value from the CardAction to be the Choice.Value if Choice.Value is null.

[bug]

I’m willing to help, just tell me where.

[mdrichardson]

PromptOptions is a set of options that you pass to a Prompt.

For a ChoicePrompt, it’s the object that contains the Choices.

[baruchiro]

I was too deep and missed the base.