Quiero generar un pdf con itext 7, pero nos sucede algo incorrecto:

com.itextpdf.kernel.PdfException: Pdf indirect object belongs to other PDF document. Copy object to current pdf document.
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:195) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:185) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:115) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:187) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:115) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:187) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfOutputStream.write(PdfOutputStream.java:115) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfWriter.writeToBody(PdfWriter.java:383) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfWriter.flushObject(PdfWriter.java:289) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfDocument.flushObject(PdfDocument.java:1572) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfObject.flush(PdfObject.java:159) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfObject.flush(PdfObject.java:127) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfObjectWrapper.flush(PdfObjectWrapper.java:94) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfPage.flush(PdfPage.java:495) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfPage.flush(PdfPage.java:454) ~[kernel-7.0.2.jar:na]
at com.itextpdf.kernel.pdf.PdfDocument.close(PdfDocument.java:785) ~[kernel-7.0.2.jar:na]
at com.itextpdf.layout.Document.close(Document.java:120) ~[layout-7.0.2.jar:na]
at com.xcz.afbp.thirdparty.service.impl.GeneratePDFService.generatePDF(GeneratePDFService.java:160) ~[classes/:na]

mi código de generación:

public void generatePDF(CreditQueryData creditQueryData, Map<String, UserCreditContentView> contentViewMap, List<PackageCreditContentView> needRetrievedCreditContentList, File pdfFile, BigDecimal score) throws Exception {

    if (!pdfFile.exists()) {
        boolean x = pdfFile.createNewFile();
        if (!x) {
            LOG.error("生成文件出错" + pdfFile.getPath());
            return;
        }
    }

    PdfDocument pdf = new PdfDocument(new PdfWriter(new FileOutputStream(pdfFile)));
    Document document = new Document(pdf, PageSize.A4);
    document.setRenderer(new DocumentRenderer(document));

    pdf.addEventHandler(PdfDocumentEvent.END_PAGE, new WatermarkingEventHandler());

    try {
        //operate code just add tableA tableB tableC...

    } catch (Exception e) {
        LOG.info();
    } finally {
        document.close(); //exception throws here
    }


}

mi único código de estilo en itext7:

 private PdfFont bfChinese = null;

se invocará init en el constructor del servicio:

 public GeneratePDFService() {
    String PdfFontPath = EnvironmentUtils.getClasspathFilePath("font/MSYH.TTF");
    try {
        bfChinese =  PdfFontFactory.createFont(PdfFontPath, "Identity-H", true);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

He intentado configurar mi fuente enestático, pero no funciona.

esta es la excepción de lanzamiento de lugar:

private void write(PdfIndirectReference indirectReference) {
        if (document != null && !indirectReference.getDocument().equals(document)) {
            throw new PdfException(PdfException.PdfIndirectObjectBelongsToOtherPdfDocument);
        }
        if (indirectReference.getRefersTo() == null) {
            write(PdfNull.PDF_NULL);
        } else if (indirectReference.getGenNumber() == 0) {
            writeInteger(indirectReference.getObjNumber()).
                    writeBytes(endIndirectWithZeroGenNr);
        } else {
            writeInteger(indirectReference.getObjNumber()).
                    writeSpace().
                    writeInteger(indirectReference.getGenNumber()).
                    writeBytes(endIndirect);
        }
    }

significa que tengo dos documentos diferentes, pero no sé cuándo he creado otro documento. Gracias de antemano por las sugerencias.