http://hg.openjdk.java.net/hsx/hotspot-rt/jdk/rev/29f979efbabf introduced a NullPointerException is some cases with `isAssignable(Class<?> current, Class<?> candidate)` when candidate is null. This happens in `if (isAssignable(gpd.getPropertyType(), pd.getPropertyType())) {`, leading to a NPE being thrown. This does not occur in Java 7 and is not documented in any way.
