@@ -0,0 +1,255 @@
+package npe;%0A%0Apublic class ComparisonWithThis %7B%0A%09int f(Object x, boolean b) %7B%0A%09%09if (x == null) System.out.println(%22x is null%22);%0A%09%09if (b) System.out.println(%22b is true%22);%0A%09%09// at this point, X is NCP%0A%09%09if (x == this) return 0;%0A%09%09return x.hashCode();%0A%09%7D%0A%0A%7D%0A

Test case showing we could detect more errors if we realized that if a value is equal to a nonnull value, then it must be nonnull as well.