aspose pdf java版本-->11.8
我尝试使用headerfooter类将标题添加到pdf文件的每个页面。下面是代码，
is——这个变量流包含html的流内容。
htmloptions—用于设置生成文件的页边距。

Document pdfDocument = new Document( is, htmloptions );

            Iterator<Page> pages = pdfDocument.getPages().iterator();
            while( pages.hasNext() ){

                Page pageCollection = pages.next();

                HeaderFooter header = new HeaderFooter();
                Paragraphs headParagraph = new Paragraphs();

                HtmlFragment headfragment = new HtmlFragment( pdfHeaderContent );
                headfragment.setVerticalAlignment( VerticalAlignment.Top );
                MarginInfo marginInfo = new MarginInfo();
                marginInfo.setLeft( 10d );
                marginInfo.setRight( 10d );
                marginInfo.setBottom( 10d );
                marginInfo.setTop( 10d );
                header.setMargin( marginInfo );
                headParagraph.add( headfragment );
                header.setParagraphs( headParagraph );

                pageCollection.setHeader( header );

            }

请告诉我如何设置收割台的高度？