Three not continiuing asterisks breaks parsing

[AlexanderLohmeyer]

Hey,
the following String does not get parsed correctly:
***Test1* Test2 *Test3*** leads to a non-correct parsing result.

Its supposed to parse everything bold and Test1 + Test3 italic. But the output is everything Italic and nothing bold (instead the asterisks gets rendered).

CommonMark Demo

It also works fine when I use Underline instead of asterisk when mark words as italic.