Shall we change eventenvelope to be compliant with CloudEvents?

## What are the schemas that are affected by the issue
`eventenvelope`
## What are examples of products that are impacted by the issue
Adobe I/O Events
## The issue: CloudEvents

In the last year, the XDM committee worked on and agreed upon a schema for events[1], which we decided to base on activity streams[2]. This seemed like a good approach at the time, as it is a W3C recommendation, and it matched to a good extent what we needed with minor adaptations.

Since then, a new open standard has begun to gather considerable momentum, Cloud Events[3], sponsored by the Cloud Native Computing Foundation[4] under the Serverless Working Group[5], and with many, many important contributors[6], including Google, Microsoft (see for example [7]), Amazon, etc.

Adobe I/O Events went live at Summit in March of this year using XDM-based events. We are wondering at this juncture what we should do about this new turn of events (pun intended :)

One possibility is that we offer our customers the choice to consume I/O Events in either format: XDM and/or CloudEvents. Microsoft’s Event Grid, for example, supports its own proprietary event schema, as well as CloudEvents [8].

A different option is to acknowledge that we may have backed the wrong horse by choosing activity streams earlier, and rectify it now, before it is too late.

I’m opening this issue in github in order to gather the opinions of the members of the XDM committee, before making a formal recommendation, or posting a PR with actual changes. I have already heard from a few members endorsing the idea of switching our standard to CloudEvents, and would like to hear further feedback from others.

[1] https://github.com/adobe/xdm/blob/master/schemas/common/eventenvelope.schema.json
[2] https://www.w3.org/TR/activitystreams-core/
[3] https://github.com/cloudevents/spec
[4] https://www.cncf.io/
[5] https://github.com/cncf/wg-serverless
[6] https://github.com/cloudevents/spec/blob/master/community/contributors.md
[7] https://azure.microsoft.com/en-us/blog/announcing-first-class-support-for-cloudevents-on-azure/
[8] https://docs.microsoft.com/en-us/azure/event-grid/cloudevents-schema

Read schemas/common/eventenvelope.schema.json and compare it with the linked CloudEvents specification. First resolve the committee's preferred direction and compatibility scope; done means an agreed recommendation with a concrete, reviewable schema change or an explicit decision not to change it.

Written by the indexing model from the issue text.