Here are the 2 different concepts taught depending on where you learn it.
I am
exhausted, interested, bored, tired, drained etc. are all past participles used as adjectives. But some chose to see it as passive voice which is also true.
That was how it was explained to me and it seemed to work for me.
In the case of "worried", it's passive voice in my view because something caused the Japanese importors to worry, or they were made worried.
In the other concept, "worried" can be viewed as adjective.