Interpret negative short lengths properly since Java does not have an unsigned short.
Interpret negative short lengths properly since Java does not have an unsigned short.

luxiaohan/openxal-csns-luxh,EuropeanSpallationSource/openxal,luxiaohan/openxal-csns-luxh,EuropeanSpallationSource/openxal,openxal/openxal,openxal/openxal,openxal/openxal,luxiaohan/openxal-csns-luxh,EuropeanSpallationSource/openxal,luxiaohan/openxal-csns-luxh,openxal/openxal,openxal/openxal,EuropeanSpallationSource/openxal,EuropeanSpallationSource/openxal