memory leak. change string value through dll by reference

[betterandhappier]

c#:

        [DllExport]

        static void test_change_string_value_by_reference([In, Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder my_str)

        {

            my_str.Clear();

            my_str.Append("here is the string from c#.net ");

        }

mql5:

#import "dll_test.dll"

void  test_change_string_value_by_reference(string & str);

#import

void OnStart()

  {

   string my_str="";

   test_change_string_value_by_reference(my_str);

   Print("new_value_of_str: ",my_str);

  }