code: public static XWPFRun getNewRun(ParagraphAlignment alignment) {
          createXwpfDocumentIfNull();
          XWPFParagraph paragraph = xwpfDocument.createParagraph();
          paragraph.setAlignment(alignment);
          return paragraph.createRun();
      }
docs: 获取一个新的XWPFRun对象
  
  @param alignment 对齐方式
  
  @return {@link XWPFRun}