ODSingleXMLDocument.createFromStream error

[jeds...@gmail.com]

Hello, I am trying to concatenate 2 odt files, but I am getting an exception at this line:

ODSingleXMLDocument.createFromStream(is)

error: exception in thread "main" org.jdom.input.JDOMParseException: Error on line 1: Content is not allowed in prolog.

source code:

package com.mycompany.jopendocument;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import org.jdom.JDOMException;

import org.jopendocument.dom.ODSingleXMLDocument;

import org.jopendocument.dom.OOUtils;

public class Main {

    public static void main(String[] args) throws JDOMException, IOException {

        File f1 = new File("c:/arquivos/arquivo1.odt");

        InputStream is = new FileInputStream(f1);

        ODSingleXMLDocument p1 = ODSingleXMLDocument.createFromStream(is);

        File f2 = new File("c:/arquivos/arquivo2.odt");

        ODSingleXMLDocument p2 = ODSingleXMLDocument.createFromPackage(f2);

        p1.add(p2);

        OOUtils.open(p1.saveToPackageAs(new File("cat")));

    }

}

The method createFromPackage works, but createFromStream does not work.