The testing the attached file on windows, it is considered as an invalid PDF/A with that error :
The fileOPM_pdfa.pdf is not valid, error(s) :
1.1 : Body Syntax error, Second line must contains at least 4 bytes greater than 127
The same file is valid in a linux environment.
I think the problem comes from a defined charset in PreflightParser. The attached patch fixes the problem.