[Subscription API] subscription.filter is not fully defined

[n3wscott]

The spec is inconsistent on how it defines the subscription.filter property. It has a sub-section but the top-level object is not defined like the rest of the properties in the spec.

See : https://github.com/cloudevents/spec/blob/master/subscriptions-api.md

Example: look for the type definition of dialect or filters. They are missing.

Additionally, it would be more clear to call out that subscription.filter is intended to be this object that is .dialect and .filters

Question: Can we bump this object up one level and allow subscription.filterdialect and subscription.filters ?

[clemensv]

ACK