This is from bug 7002070, but this part should be considered separately from the more trivial 7002070. Compiler reports SErializable as the incompatible type in a multicatch clause. Can interfaces be ignored in this process (may not reach the full lub computation)?
8<----------test----------------
/** should not be able to catch any type of Objects, just Throwables */
public class neg01 {
  public void test(String e) {
  try {
    switch (e) {
case "A":
       throw new ExceptionA("an ExceptionA");
case "B":
       throw new ExceptionB("an ExceptionB");
case "R":
       throw new RuntimeException("a RuntimeException");
default:
throw new Throwable("a throwable");
   }
}catch(final ExceptionA|ExceptionB|RuntimeException|String E ) {
}catch(Throwable t) {} /* ^^^^^ incompatible type */
}

}

class ExceptionA extends Exception {
 public ExceptionA() { super(); }
 public ExceptionA(String msg) { super(msg); }
}

class ExceptionB extends Throwable {
 public ExceptionB() { super(); }
 public ExceptionB(String msg) { super(msg); }
}
---------------------------
Error message
neg01.java:15: incompatible types
        }catch(final ExceptionA|ExceptionB|RuntimeException|String E ) {
                     ^
  required: Throwable
  found: Serializable
1 error