As a developer, I would like a field on an incoming intent request payload that tells me whether that request was the result of a barge-in or not.

Rationale:
Today, there is no way to know whether an incoming intent in a live session was the result of the user completely listening to the previous response, or the result of the user doing a barge-in by invoking their wake word. There are several use cases where this information would be useful, but the two most important are:

1. If you were giving instructions to your user at the end of your response, and they barged in, it is likely that they did not hear the information that you think you gave them. Ergo, you should repeat it at a later time.
2. If users are regularly barging in to your responses for a given interaction, that tells you that your responses are too wordy and probably need to be shortened to provide a better user experience.