Trouble with conversion from pdf to pdf/a using jobconverter

Trying to convert pdf to pdf/a using http://kapion.ru/convert-to-pdfa-with-jodconverter/ guide.

After execution getting encoded pdf file. it looks like:

%PDF-1.5
%µµµµ
1 0 obj
<</Type/Catalog/Pages 2 0 R/Lang(de-CH) /StructTreeRoot 17 0 R/MarkInfo<</Marked 
true>>>>
endobj
2 0 obj

code:

@Test
public void a() throws OfficeException {
    OfficeManager officeManager = LocalOfficeManager.make();
    DocumentConverter converter = LocalConverter.make(officeManager);
    try {
        officeManager.start();
        File inputFile = new File("C:/Users/user/Desktop/9.pdf");
        File pdfFile = new File("C:/Users/user/Desktop/Output/9.pdf");
        DocumentFormat pdfFormat = getDocumentFormatPDFA();
        converter.convert(inputFile).to(pdfFile).as(pdfFormat).execute();
    } catch (OfficeException e) {
        e.printStackTrace();
    } finally {
        if (officeManager.isRunning())
            officeManager.stop();
    }
}

private static DocumentFormat getDocumentFormatPDFA() {
    // PDF/A version
    final int PDFX1A2001 = 1;
    final Map<String, Integer> pdfOptions = new HashMap<>();
    pdfOptions.put("SelectPdfVersion", PDFX1A2001);
    return DocumentFormat.builder()
            .inputFamily(DocumentFamily.TEXT)
            .name("PDF/A")
            .extension("pdf")
            .mediaType("pdf")
            .storeProperty(DocumentFamily.TEXT, "FilterData", pdfOptions)
            .storeProperty(DocumentFamily.TEXT, "FilterName", "writer_pdf_Export")
            .unmodifiable(false)
            .build();
}

Could you, please, help me with that?

OpenOffice does not support pdf reading. The way how it is could be possible to convert pdf using external libs into docx\html, then convert it into pdf/a using OpenOffice.