This idiom causes warnings to be generated with latest javac:

                     try {
                         task.run();
                     } catch (RuntimeException x) {
                         thrown = x; throw x;
                     } catch (Error x) {
                         thrown = x; throw x;
                     } catch (Throwable x) {
                         thrown = x; throw new Error(x);
                     } finally {
                         afterExecute(task, thrown);
                     }


This is a frequent idiom in the JDK - note that the last catch clause is not entirely redundant as it can catch checked exceptions coming from a Class.newInstance call (which is transparent w.r.t. exceptions in the constructor).