added sample comparator code and tidied up some test cases & converted them to the cleaner JUnit 4 style

libraries/stdlib/src/JavaUtil.kt

@@ -53,7 +53,7 @@ inline fun <in T: java.lang.Comparable<T>> List<T>.sort() : List<T> {
   return this
 }
 
-inline fun <in T: java.lang.Comparable<T>> List<T>.sort(comparator: java.util.Comparator<T>) : List<T> {
+inline fun <in T> List<T>.sort(comparator: java.util.Comparator<T>) : List<T> {
   Collections.sort(this, comparator)
   return this
 }

libraries/stdlib/src/Ordering.kt

@@ -58,9 +58,7 @@ private class FunctionComparator<T>(val functions: Array<Function1<T,Any?>>):  C
     }
 
     override fun compare(o1: T?, o2: T?): Int {
-        // TODO compile error
-        //return compareBy<T>(o1, o2, functions)
-        throw UnsupportedOperationException("TODO")
+        return compareBy<T>(o1, o2, *functions)
     }
 
     override fun equals(obj: Any?): Boolean {