SSIS 2017 - Programmatically create script component as transformation

I am trying to create a script component as transform programmatically (not manually going inside script component) but i am unable to update main.cs file, i am getting below error.

Am i missing something, Any help would be appreciated.

FYI if i set second parameter in CreateNewProject to true i.e. "host.CreateNewProject(Guid.NewGuid().ToString("N"), true, true)", i am able to generate script component correctly but my changes done using PutSourceCode is not working.

Code:

IDTSComponentMetaData100 _ScriptComponent = pipeline.ComponentMetaDataCollection.New();
                _ScriptComponent.ComponentClassID = typeof(Microsoft.SqlServer.Dts.Pipeline.ScriptComponentHost).AssemblyQualifiedName;

                // Get the design time instance of the derived column
                var DesignScriptComponent = _ScriptComponent.Instantiate();
                DesignScriptComponent.ProvideComponentProperties();        //design time

                //VSTAScriptingEngine
                // Create a Precedence Constraint between derived column and OLEDB Destination Components
                var path = pipeline.PathCollection.New();
                path.AttachPathAndPropagateNotifications(pipeline.ComponentMetaDataCollection[Prev_Transform.Transformation_Name].OutputCollection[Prev_Transform.Output_Number],
                        _ScriptComponent.InputCollection[0]);

                // Get the list of available columns
                var ScriptComponentInput = _ScriptComponent.InputCollection[0];
                var ScriptComponentvInput = ScriptComponentInput.GetVirtualInput();
                var ScriptComponentVirtualInputColumns = ScriptComponentvInput.VirtualInputColumnCollection;

                string scriptValue = @"using System;
                                        using System.Data;
                                        using Microsoft.SqlServer.Dts.Pipeline.Wrapper;
                                        using Microsoft.SqlServer.Dts.Runtime.Wrapper;
                                        [Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute]
                                        public class ScriptMain : UserComponent
                                        {
                                          public override void PreExecute()
                                            {
                                                base.PreExecute();
                                            }
                                         public override void PostExecute()
                                            {
                                                base.PostExecute();
                                            }
                                         public override void Input0_ProcessInputRow(Input0Buffer Row)
                                            {
                                                //sam generated this
                                            }
                                        }";
                //
                //DesignScriptComponent.SetComponentProperty("ScriptLanguage","Microsoft Visual C# 2017" );
                //DesignScriptComponent.SetComponentProperty("VSTAProjectName","CustomTransform1.csproj");

                ScriptComponentHost host = (DesignScriptComponent as IDTSManagedComponent100).InnerObject as ScriptComponentHost;
                host.CreateNewProject(Guid.NewGuid().ToString("N"), false, true);
                host.PutSourceCode("main.cs", "UTF8", scriptValue);
                host.SaveScriptProject();
                //string[] sourcecode_array= _ScriptComponent.CustomPropertyCollection["SourceCode"].Value;
                //// when counted manually array 9 had main.cs
                //sourcecode_array[9] = scriptValue;
                //DesignScriptComponent.SetComponentProperty("SourceCode", sourcecode_array);

Error

Validation error. Data Flow Task: Data Flow Task: Microsoft.SqlServer.Dts.Pipeline.CannotCreateUserComponentException: Cannot create user component class. Make sure there is one class marked with SSISScriptComponentEntryPointAttribute in your script.
   at Microsoft.SqlServer.Dts.Pipeline.VSTAComponentScriptingEngine.CreateScriptObjectHelper(Assembly scriptAssembly)
   at Microsoft.SqlServer.Dts.Pipeline.VSTAComponentScriptingEngine.GetScriptEntryPoint(String versionGuid)
   at Microsoft.SqlServer.Dts.Pipeline.ScriptComponentHost.CreateUserScriptInstance()

Sam