Workaround for Microsoft SQLServer Reporting Service (SSRS) 2012, which generates invalid docx
User can override org/docx4j/jaxb/mc-preprocessor.xslt with an xslt on their classpath named custom-preprocessor.xslt
Handle potential NPE
*API change*  getContents now throws Docx4JException, instead of returning null in the case of error.
Fix package name used in reflection.