We do support the use of [Async] on methods that do not return void,
we generate an overload with am out parameter to retrieve the returned value
```csharp
[CompilerGenerated]
public unsafe virtual Task BarStringAsync (int arg1)
{
var tcs = new TaskCompletionSource<bool> ();
var result = BarString(arg1, (obj_) => {
if (obj_ != null)
tcs.SetException (new NSErrorException(obj_));
else
tcs.SetResult (true);
});
return tcs.Task;
}
[CompilerGenerated]
public unsafe virtual Task BarStringAsync (int arg1, out string result)
{
var tcs = new TaskCompletionSource<bool> ();
result = BarString(arg1, (obj_) => {
if (obj_ != null)
tcs.SetException (new NSErrorException(obj_));
else
tcs.SetResult (true);
});
return tcs.Task;
}
```
Modified the introspection test to repor this, updated documentation
and update API definitions reported by introspection.