final case class PluginAttach(address: String, unknownFields: UnknownFieldSet) extends GeneratedMessage, Updatable[PluginAttach]
PluginAttach is used to attach an already running plugin to the engine.
Normally the engine starts the plugin process itself and passes the engine address as the first argumnent. But when debugging it can be useful to have an already running provider that the engine instead attaches to, this message is used so the provider can still be passed the engine address to communicate with.