Need more info on this.
If the Israeli backpacker was alone, it's extremely unlikely he would be provoking four people of any kind.
The Germans? Perhaps middle eastern immigrant type of Germans?
How was the Israeli identified?
Well if he was alone not from speaking unless on a phone.
Hebrew or an Israeli accent is very easy to place.
Appearance? Believe it or not, even without wearing flags and such, Israelis are often easy to identify that way as well in a different way than visible Jews in general.
If the Germans were middle eastern origin, that much easier for them.
Googling this. I am seeing some international press is making a thing that the Israeli was an IDF soldier. The majority of Israelis are obligated to serve in the IDF in one way or another.