Reduce subsystem interface implementation requirements

src/EventStore.Plugins/Subsystems/ISubsystem.cs

@@ -1,5 +1,4 @@
-using System.Collections.Generic;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -8,6 +7,6 @@ namespace EventStore.Plugins.Subsystems;
 public interface ISubsystem {
 	IApplicationBuilder Configure(IApplicationBuilder builder);
 	IServiceCollection ConfigureServices(IServiceCollection services);
-	IReadOnlyList<Task> Start();
-	void Stop();
+	Task Start();
+	Task Stop();
 }

src/EventStore.Plugins/Subsystems/ISubsystemFactory.cs

@@ -1,5 +1,5 @@
 namespace EventStore.Plugins.Subsystems;
 
-public interface ISubsystemFactory<TArg> {
-	ISubsystem Create(TArg arg);
+public interface ISubsystemFactory {
+	ISubsystem Create();
 }

src/EventStore.Plugins/Subsystems/ISubsystemsPlugin.cs

@@ -3,10 +3,9 @@
 namespace EventStore.Plugins.Subsystems;
 
 // A plugin that can create multiple subsystems.
-// A TArg is required to produce each subsystem from its respective factory.
-public interface ISubsystemsPlugin<TArg> {
+public interface ISubsystemsPlugin {
 	string Name { get; }
 	string Version { get; }
 	string CommandLineName { get; }
-	IReadOnlyList<ISubsystemFactory<TArg>> GetSubsystemFactories(string configPath);
+	IReadOnlyList<ISubsystemFactory> GetSubsystemFactories(string configPath);
 }