If you are talking about the content inside the [..], then I'd agree that it contains an AOH.
From my perspective, the outermost 'main_data' => [...
indicates that it is either a hash or hashref. Of course, the programmer could be misusing the "=>" instead of a comma, making the outermost element an array, but that is marginally perverse.
So. in the absence of information to the contrary, I'll stick with my interpretation of HOAOH.
Have you been high today? I see the nuns are gay! My brother yelled to me...I love you inside Ed - Benny Lava, by Buffalax