Results 2 issues of Acela

hello, when I use docx4j-ImportXHTML convert a html file to docx file,I got a lot of logs like these: 08:58:00.308 [http-nio-8080-exec-3] WARN o.d.c.in.xhtml.XHTMLImporterImpl 784 - Skipping clip .. (null value)...

When processing concurrently, you will receive a Warning: You did not close a PDF Document. May I ask, what is the situation? How to handle it? I am using OracleJDK1.8....