Apologies for the late reply.

Do you mean C# source code? An example would be:
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class MyClass {
public Func<int,int> MyFuncA;
public Func<int,int,int> MyFuncB;
}
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If you try to recreate this in Astah by making a C# project, adding a class, and adding these two attributes: it breaks on adding MyFuncB (of type Func<int,int>). It adds a question mark to the type parameters of MyFuncA. Screenshot:



When you export it also adds this question mark to the source code. As you can see Astah does not support generic classes that have the same name but a different amount of generic parameters, even though they exist in C#.