I just received an some exceptions saying that the @XmlRootElement is missing on some of the generated classes in the wml package. In my run I spotted the following classes:
org.docx4j.wml.CTTblCellMar
org.docx4j.wml.CTShortHexNumber
org.docx4j.wml.TblWidth
org.docx4j.wml.TblBorders
org.docx4j.wml.CTTblLayoutType
Once added the annotation manually the exceptions are gone but changing a generated class manually sounds like a very bad idea for me. Could you please regenerate that classes with the appropriate XmlRootElement anotations.