Getting rid of "No -tsa or -tsacert is provided" when signing APKs

Since JDK 1.7u51 Oracle introduced some extra strictness to the jarsigner, which is fine. Although, a lot of you might have seen some warnings when Xamarin.Android signs your APK, something in the lines of:

No -tsa or -tsacert is provided and this jar is not time stamped. Without a timestamp, users may not be able to validate this jar after the signer certificate's expiration date (2xxx-xx-xx) or after any future revocation date.
I am using a property group like this in my csproj file, which defines where my keystore is and which passwords it has, for convenience:

I could not find any options to add parameters to the jarsigner command, but I did notice, that the alias always came in the end of the jarsigner command in the output window. So my small workaround is to simply append the alias with -tsa, which removes the warning (yay!)
So now the property group looks like:

Although, I have recently put up APK files on the Play Store without this hack to remove the warnings and they were accepted just fine. So I guess... do whatever you want ;)