XDocReport means XML Document reporting. It's Java API to merge XML document created with MS Office (docx) or OpenOffice (odt), LibreOffice (odt) with a Java model to generate report and convert it if you need to another format (PDF, XHTML...).
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window xdocreport-xdocreport-parent.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.
