While googling the error
java.lang.IllegalArgumentException: Comparison method violates its general contract!
I found it's related to pdfbox and has been fixed in version 1.8.8+ (see issues. apache. org/jira/browse/PDFBOX-1512)
So i've unzipped PdfBoxPreparator.jar and injected the latest precompiled pdfbox 1.8.10, rezipped to a jar file and here we go !
Any change to update pdfbox in the next release ?