Generation creates uncompilable code for complex types with primitives

[Urist-McGit]

The code generation fails when using a more complex data structure in the interface. The most simple example interface is this:

<interface name="org.example">
  <method name="ExampleMethod">
    <arg type="(ai)" name="exampleArg"/>
  </method>
</interface>

This creates uncompilable code. The cause is that the generated code contains type arguments that are primitives, in the above case int instead of Integer. This replacement works when the arguments are not in a struct, so e.g. ai as argument type above would work. I looked into the code and it seems like the recursive creation of struct members does not take care of the replacement of primitives in type arguments.