AuthorizeConnection with filters (#2734)

* AuthorizeConnection with filters

internal/daemon/controller/common/common.go

@@ -27,3 +27,11 @@ type (
 	ConnectionRepoFactory        func() (*session.ConnectionRepository, error)
 	WorkerAuthRepoStorageFactory func() (*server.WorkerAuthRepositoryStorage, error)
 )
+
+// Downstreamers provides at least a minimum interface that must be met by a
+// Controller.downstreamWorkers field which is far better than allowing any (empty
+// interface)
+type Downstreamers interface {
+	// RootId returns the root ID of the downstreamers' graph
+	RootId() string
+}