Observation#wrapChecked(CheckedCallable<T,E>) should not throw E itself

[nobeh]

Describe the bug

io.micrometer.observation.Observation#wrapChecked(Observation.CheckedCallable<T,E>) is as follows:

default <T, E extends Throwable> CheckedCallable<T, E> 
    wrapChecked(CheckedCallable<T, E> checkedCallable) throws E {
        return () -> observeChecked(checkedCallable);
}

It wraps around a Callable that throws E. The return of this method is another Callable that would delegate to the provided code and also makes an observation.

If we rewrite the method as:

default <T, E extends Throwable> CheckedCallable<T, E> 
    wrapChecked(CheckedCallable<T, E> checkedCallable) throws E {
        var observedCallable = () -> observeChecked(checkedCallable);
        return observedCallable;
}

Then there is no need that the method wrapChecked should also throw E. The wrapping logic should not encounter any exception. I think this might have been a mistake during design or compilation.

[shakuzen]

Thanks for the report. That does seem like a mistake. The problem is I think while it would be binary compatible to remove the checked exception (throws), I don't think it would be source compatible.