Using SimpleDoc() with DocFlavour String (not InputStream)

When trying to use SimpleDoc I get this error:

Exception in thread "main" java.lang.IllegalArgumentException: data is
not of declared type
    at javax.print.SimpleDoc.<init>(Unknown Source)
    at PrintPsString.main(PrintPsString.java:32)

No doubt because I am specifying a DocFlavour of INPUT_STREAM
(DocFlavor.INPUT_STREAM.POSTSCRIPT) and supplying a String.

Unfortunately DocFlavor.STRING doesn't include a
DocFlavor.STRING.POSTSCRIPT and using
DocFlavor.STRING.TEXT_PLAIN I get no available printers

I can make it work if I assign a FileInputStream to a file containing
the same data. What can I do to print data created dynamically in my
program?

------------------------------8<------------------------------
import javax.print.Doc;
import javax.print.DocFlavor;
import javax.print.DocPrintJob;
import javax.print.PrintException;
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
import javax.print.SimpleDoc;
import javax.print.attribute.HashPrintRequestAttributeSet;
import javax.print.attribute.PrintRequestAttributeSet;

public class PrintPsString {
     public static void main(String[] args) {

         // data to be printed
         StringBuffer sb = new StringBuffer();
         sb.append("%!PS\n");
         sb.append("/Helvetica 24 selectfont\n");
         sb.append("100 700 moveto\n");
         sb.append("(Simple Postscript) show\n");
         sb.append("showpage\n");

         // select target printer
         DocFlavor flavor = DocFlavor.INPUT_STREAM.POSTSCRIPT;
         PrintRequestAttributeSet aset = new
                 HashPrintRequestAttributeSet();
         PrintService[] pservices = PrintServiceLookup
                 .lookupPrintServices(flavor, aset);
         if (pservices.length == 0) {
             System.out.println("No suitable printers");
             System.exit(0);
         }
         DocPrintJob pj = pservices[0].createPrintJob();
         System.out.printf("Printing to '%s' \n",
                 pservices[0].getName());

         // printable 'document'
         String s = sb.toString();
         Doc doc = new SimpleDoc(s, flavor, null);

         // print it
         try {
             pj.print(doc, aset);
             System.out.println("Your document has been Printed");
         } catch (PrintException e) {
             e.printStackTrace();
             System.out.println(e.getMessage());
         }

     }
}
------------------------------8<------------------------------