SinkProvider
A Sink of the streams a service publishes: what opens the Sinks of one destination, a warehouse's tables say. Wow's ClickHouse Sink (clickhouse) is a provider as a community one is: the host finds them on the classpath (ServiceLoader, from the module's META-INF/services/me.ahoo.wow.spi.sink.SinkProvider) and among the application's beans, a bean taking the place of a provider of its type on the classpath, as it finds a me.ahoo.wow.spi.store.StoreProvider, and runs one sink subscription per published stream over what it opens.
A provider is stateless: open gives each configured sink its own StreamSinks, over the settings SinkConfig.options holds and the application's SinkConfig.resources (the service's Manifest among them).
Properties
Every setting it reads from SinkConfig.options, each read through its option, for the host to bind and check (wow.<type>.<key>). A ProviderOption.Scope.PER_STORE option is one the host gives the sink itself, not set under wow.<type> (the ClickHouse Sink's per-aggregate aggregates.*).
What a sink of this type needs, in the words of a startup failure that says it is missing.