@@ -0,0 +1,850 @@
+package sfBugs;%0D%0A%0D%0Aimport java.io.IOException;%0D%0A%0D%0Apublic class Bug1964520 extends Exception %7B%0D%0A    private static final long serialVersionUID = 1L;%0D%0A%0D%0A%09public void test(Exception e) %7B%0D%0A%09%09// should trigger warning (and does)%0D%0A%09%09if(((Bug1964520)e).toString().equals(%22%22)) %7B%0D%0A%09%09%09System.out.println(%22toString is blank%22);%0D%0A%09%09%7D%0D%0A%09%09// should trigger warning (and does)%0D%0A%09%09if(e instanceof IOException && ((Bug1964520)e).toString().equals(%22%22)) %7B%0D%0A%09%09%09System.out.println(%22toString is blank%22);%0D%0A%09%09%7D%0D%0A%09%09// should not trigger warning (and doesn't)%0D%0A%09%09if(e instanceof Bug1964520 && ((Bug1964520)e).toString().equals(%22%22)) %7B%0D%0A%09%09%09System.out.println(%22toString is blank%22);%0D%0A%09%09%7D%0D%0A%09%09// should not trigger warning (and doesn't)%0D%0A%09%09if(e instanceof Bug1964520) %7B%0D%0A%09%09%09if(((Bug1964520)e).toString().equals(%22%22)) %7B%0D%0A%09%09%09%09System.out.println(%22toString is blank%22);%0D%0A%09%09%09%7D%0D%0A%09%09%7D%0D%0A%09%7D%0D%0A%7D%0D%0A

Test case for [ 1964520 ] Findbugs reports invalid M D BC - Unchecked/unconfirmed cast (I can't recreate it)