[VFS-520] Make javadoc compatible with javadoc tool from java 8. (there are still 100 warnings mostly about missing @return and @param)

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/vfs/trunk@1591516 13f79535-47bb-0310-9956-ffa450edef68
[VFS-520] Make javadoc compatible with javadoc tool from java 8.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/vfs/trunk@1591517 13f79535-47bb-0310-9956-ffa450edef68