支持导出启动过程被重写

因为有很多业务需要重写处理逻辑

src/dotnetCampus.ApplicationStartupManager/StartupManager.cs

@@ -312,17 +312,6 @@ namespace dotnetCampus.ApplicationStartupManager
 
             return DFSGraph(wrappers);
 
-            IEnumerable<StartupTaskMetadata> ExportStartupTasks()
-            {
-                foreach (var func in _startupTaskMetadataCollectorList)
-                {
-                    foreach (var taskMetadata in func())
-                    {
-                        yield return taskMetadata;
-                    }
-                }
-            }
-
             void AddDependencies(StartupTaskWrapper wrapper, string afterTasks)
             {
                 foreach (var task in afterTasks.Split(new[] {';'}, StringSplitOptions.RemoveEmptyEntries)
@@ -364,6 +353,18 @@ namespace dotnetCampus.ApplicationStartupManager
             }
         }
 
+        protected virtual IEnumerable<StartupTaskMetadata> ExportStartupTasks()
+        {
+            foreach (var func in _startupTaskMetadataCollectorList)
+            {
+                var taskMetadataList = func();
+                foreach (var taskMetadata in taskMetadataList)
+                {
+                    yield return taskMetadata;
+                }
+            }
+        }
+
         private static string CompatibleTaskName(string task)
         {
             const string startupName = "Startup";