I did receive a European 5 watt USB charger model A1400 that claims to be from Apple. The charger even claims to be designed by Apple in California and made in China. Possibly by "Salcomp".
The "made in China" part, is most likely a valid claim.
But how can I find out whether this USB charger is a counterfeit or a genuine Apple product?
I do own a genuine A1300 that came with an iPhone that was bought in an Apple store in Oberhausen. The 230V pins two USB chargers are shown in the photograph below:
Here is a photograph of the serial imprint inside the USB connector from both an "A1400" and an original A1300:

And here the imprint the "Certification Label" of a possible counterfeit A1400:

PS I am aware of the A1300 to A1400 Exchange program and don't use the A1300 any longer for charging purposes.

