Switch to using a single event type

[mimir-d]

Issue by marcoguerri Wednesday Jun 17, 2020 at 09:09 GMT Originally opened as https://github.com/facebookincubator/contest/issues/123

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At the moment we have two type of events, testevents and frameworkevents. The former are meant to be used when emitted by a Step, the latter from anywhere in the framework outside of a Step. The intention was to enforce non-null on most of the fields of the Step.

Eventually we settled on the fact that this is too restrictive. FrameworkEvents are barely used, and lots of places of the framework need to emit events that include a subset of the information of testevents.

So, we agree on deprecating frameworkevents, and using one single concept of event, where fields might be null. In addition, this event should be associated to a "source" in the header (most likely split into SourceType and SourceName), which will indicate who emitted the event.