PDFBox api Issue in java

I am trying to write the content into PDF, I have written the below code

  public ByteArrayOutputStream createPDF(String text) throws IOException, COSVisitorException {

    PDDocument document;
    PDPage page;
    PDFont font1;
    PDPageContentStream contentStream;
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    document = new PDDocument();


    try {
      page = new PDPage();      
      document.addPage(page);
      contentStream = new PDPageContentStream(document, page);

      contentStream.beginText();
      contentStream.moveTextPositionByAmount( 100, 700 );
      contentStream.drawString("Hello World Hello World Hello World Hello World Hello World");
      contentStream.endText();
      System.out.println("output " + output);
      document.save(output);
      document.close();
      contentStream.close();    

    } catch (Exception e) {
      e.printStackTrace();

    } finally
    {
      logInfo("output completed");
    }
    return output;
  }

I can able to download the PDF ,But the PDF is Empty, but in the backend output value is look like below.

%▒▒▒▒
1 0 obj
<<
/Type /Catalog
/Version /1.4
/Pages 2 0 R
>>
endobj
2 0 obj
<<
/Type /Pages
/Kids [3 0 R]
/Count 1
>>
endobj
3 0 obj
<<
/Type /Page
/MediaBox [0.0 0.0 612.0 792.0]
/Parent 2 0 R
/Contents 4 0 R
/Resources 5 0 R
>>
endobj
4 0 obj
<<
/Filter [/FlateDecode]
/Length 6 0 R
>>
stream
x▒
endstream
endobj
5 0 obj
<<
>>
endobj
6 0 obj
8
endobj
xref
0 7
0000000000 65535 f
0000000015 00000 n
0000000078 00000 n
0000000135 00000 n
0000000247 00000 n
0000000333 00000 n
0000000354 00000 n
trailer
<<
/Root 1 0 R
/ID [<C68578F989B81BF7DD279AE1745F6E8F> <D41D8CD98F00B204E9800998ECF8427E>]
/Size 7
>>
startxref
371
%%EOF

I don't know what i missed here. Please help to fix this issue.