The first link doesn't describe an enhancement to the vararg mechanism itself. I it merely describes a situation where type-erasure for a method using varargs and generics could lead to a ClassCastException at runtime.
In fact, the compiler has always been able to detect this and report it as a warning, it's just that as of
Java 7 the way this warning is reported has changed:
Note: The Java SE 5 and 6 compilers generate this warning when the ArrayBuilder.addToList is called; in this example, the warning is generated for the class HeapPollutionExample. These compilers do not generate the warning at the declaration site. However, the Java SE 7 generates the warning at both the declaration site and the call site ...
Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
