[JBMAR-160] :  SimpleMarshallerTests.testConcurrentHashMap fails on Java 8

The ConcurrentHashMap class has been changed in JDK8. 
The fields segments, segmentMask and segmentShift are part of serialPersistentFields, which caused issues with the serial marshalling / unmarshalling.

[BZ 1074546] : https://bugzilla.redhat.com/show_bug.cgi?id=1074546