Bosch Windshield Adapter Concern

I recently purchased two sets of the Bosch Micro Edge windshield wiper
blades. I became concerned during installation when I realized that the
universal adapter does not have anything that hooks into the slot of the
windshield wiper arm to keep it from pulling off. I have installed them on
Subarus. The Bosch website indicates that the preinstalled adapter is the
correct one. Could anyone provide direction if something was done wrong
during installation or why the safety catch from the adapter to the wiper
arm slot is not needed?