DSL iText Java generation code

Hello. 

I am a newbie to Jetbrains MPS and I am wondering how to use classes from e.g java.io package inside my generator. Additionally, I want to use classes from iText inside of the generated class (because Editor2Pdf plugin seems not to be working anymore). How to do it, should I extend the Java language provided?

Here is the java code I want to achieve with the editor I have so far:

```

public class PdfGenerator {
    public static final String DEST = "results/chapter01/hello_world.pdf";

    public static void main(String args[]) throws IOException {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
        new PdfGenerator().createPdf(DEST);
    }

    public void createPdf(String dest) throws IOException {
        //Initialize PDF writer
        PdfWriter writer = new PdfWriter(dest);

        //Initialize PDF document
        PdfDocument pdf = new PdfDocument(writer);

        // Initialize document
        Document document = new Document(pdf);

        //Add paragraph to the document
        document.add(new Paragraph("Hello World!"));

        //Close document
        document.close();
    }
}


// MPS generator


root template          
input TreatmentDocument
                       
public class map_TreatmentDocument { 
   
  public static final String DEST = "results/chapter01/hello_world.pdf"; 
   
   
  public static void main(string[] args) { 
    Pdf 
  } 
   
  public void createPdf(String dest) { 
    <no statements> 
  } 
}