Ensure that the feature is not abstract before to instantiate it, and do not use reflection anymore for some clone implementation.
The reflection was used for cloning a final field. But given that the classes that used them are not so big, the risk of removing
the 'final' keyword may be reasonable.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK8@1597108 13f79535-47bb-0310-9956-ffa450edef68