Better implementation of DefaultSource.getSourceExtents() in order to avoid an UnsupportedOperationException at unmarshalling time.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK8@1606676 13f79535-47bb-0310-9956-ffa450edef68
Merge from the JDK8 branch.

git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1606677 13f79535-47bb-0310-9956-ffa450edef68