JarFilter was used solely by implementation of the extension mechanism, which itself was removed by 8064956 [1]. JarFilter should probably have been removed along with the other extension implementation, it was probably just overlooked. It should be removed.
$ hg rm src/java.base/share/classes/sun/misc/JarFilter.java -Chris. [1] https://bugs.openjdk.java.net/browse/JDK-8064956
