SinkConfig
What a SinkProvider opens its sinks from: their name and type, their own settings (options, each key relative to the sink's configuration, endpoint say), and the application's resources.
A Sink that writes into one of the node's stores, as an event search index written into an Elasticsearch store is, has that opened store, and writes the streams the host names, the aggregate types whose events that store is to serve; a Sink of a destination of its own has neither, and writes the streams the Manifest publishes.
Fields may be added: the host builds it, so the constructor is internal to Wow; a provider's test builds one with of.
Constructors
Properties
The keys of options the sink asked for, so a test can hold them to the options its provider declares.
The aggregate types this Sink writes, null for the streams the Manifest publishes.
Functions
The value of the ProviderOption.Defaulted option: its setting, parsed, else its default, so always one.