ADDITIONAL SYSTEM INFORMATION :
Java 21/ Windows

A DESCRIPTION OF THE PROBLEM :
While implementing functional interface for example, Callable, the calling function needs to handle the exception irrespective of exception being handled within the lambda expression itself.

 Callable callable = () -> {
            try {
                //do something
            } catch (Exception e) {
                //throw new Exception(e)
            }
            return "This is callable";
        };
        System.out.println(callable.call()); //this throws exception asking to handle the Exception.

For non-lambda code, using this is not mandated.
Example:


class MyCallable implements Callable {

    @Override
    public Object call() { // removed throws Exception and handled with try-catch
        try {

        } catch (Exception e) {
            //throw new RuntimeException(e);
        }
        return "This is callable";
    }
}
MyCallable myCallable=new MyCallable();
        System.out.println(myCallable.call()); //this does not throw any exception

Hence this needs to be handled, if the lambda expression itself handles the exception and does not want the calling function to handle.