билдится на старом дотнете

Example.Shared/Example.Shared.csproj

@@ -1,9 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net9.0</TargetFramework>
-        <ImplicitUsings>enable</ImplicitUsings>
+        <TargetFramework>netstandard2.1</TargetFramework>
+
         <Nullable>enable</Nullable>
+
+        <LangVersion>9</LangVersion>
     </PropertyGroup>
 
     <ItemGroup>

Example.Shared/ILoadTest.cs

@@ -1,13 +1,14 @@
 using mROA.Implementation.Attributes;
 
-namespace Example.Shared;
-
-[SharedObjectInterface]
-public interface ILoadTest
+namespace Example.Shared
 {
-    int Next(int last);
-    int Last(int next);
-    void C();
-    void A();
+    [SharedObjectInterface]
+    public interface ILoadTest
+    {
+        int Next(int last);
+        int Last(int next);
+        void C();
+        void A();
+    }
 }
 

Example.Shared/IPage.cs

@@ -1,9 +1,10 @@
 using mROA.Implementation.Attributes;
 
-namespace Example.Shared;
-
-[SharedObjectInterface]
-public interface IPage
+namespace Example.Shared
 {
-    byte[] GetData();
+    [SharedObjectInterface]
+    public interface IPage
+    {
+        byte[] GetData();
+    }
 }

Example.Shared/IPrinter.cs

@@ -1,12 +1,15 @@
+using System.Threading;
+using System.Threading.Tasks;
 using mROA.Implementation;
 using mROA.Implementation.Attributes;
 
-namespace Example.Shared;
-
-[SharedObjectInterface]
-public interface IPrinter
+namespace Example.Shared
 {
-    string GetName();
-    Task<SharedObject<IPage>> Print(string text, CancellationToken cancellationToken);
+    [SharedObjectInterface]
+    public interface IPrinter
+    {
+        string GetName();
+        Task<SharedObject<IPage>> Print(string text, CancellationToken cancellationToken);
     
+    }
 }

Example.Shared/IPrinterFactory.cs

@@ -1,15 +1,16 @@
 using mROA.Implementation;
 using mROA.Implementation.Attributes;
 
-namespace Example.Shared;
-
-[SharedObjectInterface]
-public interface IPrinterFactory
+namespace Example.Shared
 {
-    SharedObject<IPrinter> Create(string printerName);
-    void Register(SharedObject<IPrinter> printer);
-    SharedObject<IPrinter> GetPrinterByName(string printerName);
-    SharedObject<IPrinter> GetFirstPrinter();
-    string[] CollectAllNames();
+    [SharedObjectInterface]
+    public interface IPrinterFactory
+    {
+        SharedObject<IPrinter> Create(string printerName);
+        void Register(SharedObject<IPrinter> printer);
+        SharedObject<IPrinter> GetPrinterByName(string printerName);
+        SharedObject<IPrinter> GetFirstPrinter();
+        string[] CollectAllNames();
 
+    }
 }