Responding with cards sample no renderer for adaptive card

[timenick]

Describe the bug

Choose adaptive card self, it works. But when you select all cards, the last card will show No renderer for this attachment.

Version

composer stable

Screenshots

[Danieladu]

change the AllCards template from

# AllCards
[Activity
    Attachments = ${HeroCard()} | ${ThumbnailCard()} | ${SigninCard()} | ${AnimationCard()} | ${VideoCard()} | ${AudioCard()} | ${AdaptiveCard()}
    AttachmentLayout = ${AttachmentLayoutType()}
]

to

# AllCards
[Activity
    Attachments = ${HeroCard()} | ${ThumbnailCard()} | ${SigninCard()} | ${AnimationCard()} | ${VideoCard()} | ${AudioCard()} | ${json(adaptivecardjson())}
    AttachmentLayout = ${AttachmentLayoutType()}
]

The reason is that, you can not insert an activity entity into the value of attachment property.

[cwhitten]

#2752